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In the original BoringCrypto port, ecdsa and rsa's public and private
keys added a 'boring unsafe.Pointer' field to cache the BoringCrypto
form of the key. This led to problems with code that “knew” the layout
of those structs and in particular that they had no unexported fields.
In response, as an awful kludge, I changed the compiler to pretend
that field did not exist when laying out reflect data. Because we want
to merge BoringCrypto in the main tree, we need a different solution.
Using boring.Cache is that solution.
For #51940.
Change-Id: Ideb2b40b599a1dc223082eda35a5ea9abcc01e30
Reviewed-on: https://go-review.googlesource.com/c/go/+/395883
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
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One annoying difference between dev.boringcrypto and master is that
there is not a clear separation between low-level (math/big-free)
crypto and high-level crypto, because crypto/internal/boring imports
both encoding/asn1 and math/big.
This CL removes both those problematic imports and aligns the
dependency rules in the go/build test with the ones in the main
branch.
To remove encoding/asn1, the crypto/internal/boring APIs change to
accepting and returning encoded ASN.1, leaving crypto/ecdsa to do the
marshaling and unmarshaling, which it already contains code to do.
To remove math/big, the crypto/internal/boring package defines
type BigInt []uint, which is the same representation as a big.Int's
internal storage. The new package crypto/internal/boring/bbig provides
conversions between BigInt and *big.Int. The boring package can then
be in the low-level crypto set, and any package needing to use bignum
APIs (necessarily in the high-level crypto set) can import bbig to
convert.
To simplify everything we hide from the test the fact that
crypto/internal/boring imports cgo. Better to pretend it doesn't and
keep the prohibitions that other packages like crypto/aes must not use
cgo (outside of BoringCrypto).
$ git diff origin/master src/go/build/deps_test.go
diff --git a/src/go/build/deps_test.go b/src/go/build/deps_test.go
index 6ce872e297..a63979cc93 100644
--- a/src/go/build/deps_test.go
+++ b/src/go/build/deps_test.go
@@ -402,9 +402,13 @@ var depsRules = `
NET, log
< net/mail;
+ NONE < crypto/internal/boring/sig;
+ sync/atomic < crypto/internal/boring/fipstls;
+ crypto/internal/boring/sig, crypto/internal/boring/fipstls < crypto/tls/fipsonly;
+
# CRYPTO is core crypto algorithms - no cgo, fmt, net.
# Unfortunately, stuck with reflect via encoding/binary.
- encoding/binary, golang.org/x/sys/cpu, hash
+ crypto/internal/boring/sig, encoding/binary, golang.org/x/sys/cpu, hash
< crypto
< crypto/subtle
< crypto/internal/subtle
@@ -413,6 +417,8 @@ var depsRules = `
< crypto/ed25519/internal/edwards25519/field, golang.org/x/crypto/curve25519/internal/field
< crypto/ed25519/internal/edwards25519
< crypto/cipher
+ < crypto/internal/boring
+ < crypto/boring
< crypto/aes, crypto/des, crypto/hmac, crypto/md5, crypto/rc4,
crypto/sha1, crypto/sha256, crypto/sha512
< CRYPTO;
@@ -421,6 +427,7 @@ var depsRules = `
# CRYPTO-MATH is core bignum-based crypto - no cgo, net; fmt now ok.
CRYPTO, FMT, math/big, embed
+ < crypto/internal/boring/bbig
< crypto/rand
< crypto/internal/randutil
< crypto/ed25519
@@ -443,7 +450,8 @@ var depsRules = `
< golang.org/x/crypto/hkdf
< crypto/x509/internal/macos
< crypto/x509/pkix
- < crypto/x509
+ < crypto/x509;
+ crypto/internal/boring/fipstls, crypto/x509
< crypto/tls;
# crypto-aware packages
@@ -653,6 +661,9 @@ func findImports(pkg string) ([]string, error) {
}
var imports []string
var haveImport = map[string]bool{}
+ if pkg == "crypto/internal/boring" {
+ haveImport["C"] = true // kludge: prevent C from appearing in crypto/internal/boring imports
+ }
fset := token.NewFileSet()
for _, file := range files {
name := file.Name()
For #51940.
Change-Id: I26fc752484310d77d22adb06495120a361568d04
Reviewed-on: https://go-review.googlesource.com/c/go/+/395877
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
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Change-Id: Ic5f71c04f08c03319c043f35be501875adb0a3b0
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Not quite golang.org/wiki/TargetSpecific compliant, but almost.
The only substantial code change is in randFieldElement: it used to use
Params().BitSize instead of Params().N.BitLen(), which is semantically
incorrect, even if the two values are the same for all named curves.
For #52182
Change-Id: Ibc47450552afe23ea74fcf55d1d799d5d7e5487c
Reviewed-on: https://go-review.googlesource.com/c/go/+/315273
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
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Change-Id: I18dbf4f9fa7e2334fccedd862a523126cf38164e
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crypto/ecdsa was long overdue a cleanup. Bump the FIPS 186 version, and
make sure we consistently reference that and SEC 1, not the paywalled
ANSI standard.
Change-Id: Idd90bd6c14b334941fdcd829d89b796a60a8b174
Reviewed-on: https://go-review.googlesource.com/c/go/+/352529
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Trust: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
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Change-Id: I1aa33cabd0c55fe64994b08f8a3f7b6bbfb3282c
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The current code, introduced in CL 2422, mixes K bits of entropy with
the private key and message digest to generate the signature nonce,
where K is half the bit size of the curve. While the ECDLP complexity
(and hence security level) of a curve is half its bit size, the birthday
bound on K bits is only K/2. For P-224, this means we should expect a
collision after 2^56 signatures over the same message with the same key.
A collision, which is unlikely, would still not be a major practical
concern, because the scheme would fall back to a secure deterministic
signature scheme, and simply leak the fact that the two signed messages
are the same (which is presumably already public).
Still, we can simplify the code and remove the eventuality by always
drawing 256 bits of entropy.
Change-Id: I58097bd3cfc9283503e38751c924c53d271af92b
Reviewed-on: https://go-review.googlesource.com/c/go/+/352530
Trust: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>
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dev.boringcrypto
There used to be two BoringCrypto-specific behaviors related to cipher
suites in crypto/tls:
1. in FIPS-only mode, only a restricted set of AES ciphers is allowed
2. NOT in FIPS-only mode, AES would be prioritized over ChaCha20 even if
AES hardware was not available
The motivation of (2) is unclear, and BoringSSL doesn't have equivalent
logic. This merge drops (2), and keeps (1). Note that the list of
FIPS-only ciphers does not have priority semantics anymore, but the
default logic still sorts them the same way as they used to be.
Change-Id: I50544011085cfa2b087f323aebf5338c0bd2dd33
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The previous link broke, but it's available on the internet archive.
Fixes #39808
Change-Id: Ic2be74a1f0591600ca1acbe08e1bab8ba1e21abe
GitHub-Last-Rev: 6d6de5d2f451c6d53a1e55b62fb5a1fab0d49f10
GitHub-Pull-Request: golang/go#40165
Reviewed-on: https://go-review.googlesource.com/c/go/+/242103
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
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Change-Id: I083d1e4e997b30d9fab10940401eaf160e36f6c1
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Change-Id: Idd59c37d2fd759b0f73d2ee01b30f72ef4e9aee8
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Fixes #38190
Change-Id: I10766068ee18974e81b3bd78ee0b4d83cc9d1a8c
Reviewed-on: https://go-review.googlesource.com/c/go/+/231417
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>
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This CL revives CL 174437(also IBM CLA) and adds benchmarks and some simplifications.
The original commit message is as follows:
Utilize KDSA when available. This guarantees constant time operation on all three curves mentioned,
and is faster than conventional assembly.
Benchmarks:
name old time/op new time/op delta
SignP256-8 15.2µs ±14% 14.1µs ±18% ~ (p=0.356 n=9+10)
SignP384-8 4.28ms ±26% 0.02ms ±30% -99.43% (p=0.000 n=10+10)
VerifyP256-8 33.6µs ±13% 13.3µs ±38% -60.32% (p=0.000 n=9+10)
name old alloc/op new alloc/op delta
SignP256-8 2.16kB ± 0% 1.60kB ± 0% -25.63% (p=0.000 n=9+10)
SignP384-8 1.75MB ± 0% 0.00MB ± 0% -99.90% (p=0.000 n=9+10)
VerifyP256-8 1.08kB ± 0% 0.18kB ± 0% -83.70% (p=0.000 n=9+10)
name old allocs/op new allocs/op delta
SignP256-8 29.0 ± 0% 22.0 ± 0% -24.14% (p=0.000 n=10+10)
SignP384-8 14.4k ± 0% 0.0k ± 0% -99.85% (p=0.000 n=9+10)
VerifyP256-8 23.0 ± 0% 7.0 ± 0% -69.57% (p=0.000 n=10+10)
Change-Id: Ifa1fc5917fa7592dd592affa7549147dbc9b4169
Reviewed-on: https://go-review.googlesource.com/c/go/+/228580
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Munday <mike.munday@ibm.com>
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Change-Id: I2dcec316fd08d91db4183fb9d3b9afde65cc248f
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This makes all modern public keys in the standard library implement a
common interface (below) that can be used by applications for better
type safety and allows for checking that public (and private keys via
Public()) are equivalent.
interface {
Equal(crypto.PublicKey) bool
}
Equality for ECDSA keys is complicated, we take a strict interpretation
that works for all secure applications (the ones not using the
unfortunate non-constant time CurveParams implementation) and fails
closed otherwise.
Tests in separate files to make them x_tests and avoid an import loop
with crypto/x509.
Re-landing of CL 223754. Dropped the test that was assuming named curves
are not implemented by CurveParams, because it's not true for all
curves, and anyway is not a property we need to test. There is still a
test to check that different curves make keys not Equal.
Fixes #21704
Fixes #38035
Reviewed-on: https://go-review.googlesource.com/c/go/+/223754
Reviewed-by: Katie Hockman <katie@golang.org>
Change-Id: I736759b145bfb4f7f8eecd78c324315d5a05385c
Reviewed-on: https://go-review.googlesource.com/c/go/+/225460
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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This reverts CL 223754.
Reason for revert: new tests are failing on all longtest builders.
Change-Id: I2257d106c132f3a02c0af6b20061d4f9a8093c4f
Reviewed-on: https://go-review.googlesource.com/c/go/+/225077
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
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This makes all modern public keys in the standard library implement a
common interface (below) that can be used by applications for better
type safety and allows for checking that public (and private keys via
Public()) are equivalent.
interface {
Equal(crypto.PublicKey) bool
}
Equality for ECDSA keys is complicated, we take a strict interpretation
that works for all secure applications (the ones not using the
unfortunate non-constant time CurveParams implementation) and fails
closed otherwise.
Tests in separate files to make them x_tests and avoid an import loop
with crypto/x509.
Fixes #21704
Change-Id: Id5379c96384a11c5afde0614955360e7470bb1c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/223754
Reviewed-by: Katie Hockman <katie@golang.org>
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Update the Example in the crypto/ecdsa package for signing
and verifying signatures to use these new functions.
This also changes (*PrivateKey).Sign to use
x/crypto/cryptobyte/asn1 instead of encoding/asn1
to marshal the signature.
Fixes #20544
Change-Id: I3423cfc4d7f9e1748fbed5a631438c8a3b280df4
Reviewed-on: https://go-review.googlesource.com/c/go/+/217940
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
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Signing-side signature algorithm selection moved to
selectSignatureScheme, so add FIPS logic there.
Change-Id: I827e7296d01ecfd36072e2139e74603ef42c6b24
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This a revert of CL 174437 and follow up fix CL 201317.
The s390x assembly in this package makes use of an instruction
(specifically KDSA) which is not supported by the current build
machine. Remove this assembly for now, we can revisit this
functionality once we have a newer build machine and can ensure
that this assembly is well tested.
Updates #34927.
Change-Id: I779286fa7d9530a254b53a515ee76b1218821f2f
Reviewed-on: https://go-review.googlesource.com/c/go/+/201360
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Include references in the package-level comment block, expand
the obscure IRO acronym, and add a reference for "the standard
(cryptographic) assumptions".
Fixes #33589
Change-Id: I76c3b0a2f7258b3ab4bf1c8e7681c5d159720a20
GitHub-Last-Rev: 30d5a1e2fbbbb577ccc819f5ef80d5238565c9f3
GitHub-Pull-Request: golang/go#33723
Reviewed-on: https://go-review.googlesource.com/c/go/+/190840
Reviewed-by: Filippo Valsorda <filippo@golang.org>
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Change-Id: Ic1d89215bb3e37a722d3d3bc7698edea940a83d9
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merge conflicts
As suggested by dmitshur@, move them to their own block so they don't
conflict with changes in the upstream imports.
Change-Id: Id46fb7c766066c406023b0355f4c3c860166f0fe
Reviewed-on: https://go-review.googlesource.com/c/go/+/181277
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
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Utilize KDSA when available. This guarantees constant time operation on all three curves mentioned,
and is faster than conventional assembly. The IBM Z model(s) that support KDSA as used in this CL
are not yet publicly available, and so we are unable to release performance data at this time.
Change-Id: I85360dcf90fe42d2bf32afe3f638e282de10a518
Reviewed-on: https://go-review.googlesource.com/c/go/+/174437
Run-TryBot: Michael Munday <mike.munday@ibm.com>
Reviewed-by: Michael Munday <mike.munday@ibm.com>
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Change-Id: I9246c8228d38559c40e69fa403fa946ac1b31dbe
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Change-Id: I34877ac1d6d7fe9ffa7eabe46b4032af84d33794
Reviewed-on: https://go-review.googlesource.com/c/153337
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Conflicts due to randutil.MaybeReadByte (kept at the top for patch
maintainability and consistency):
src/crypto/ecdsa/ecdsa.go
src/crypto/rsa/pkcs1v15.go
src/crypto/rsa/rsa.go
Change-Id: I03a2de541e68a1bbdc48590ad7c01fbffbbf4a2b
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Code has ended up depending on things like RSA's key generation being
deterministic given a fixed random Reader. This was never guaranteed and
would prevent us from ever changing anything about it.
This change makes certain calls randomly (based on the internal
fastrand) read an extra byte from the random Reader. This helps to
ensure that code does not depend on internal details.
I've not added this call in the key generation of ECDSA and DSA because,
in those cases, key generation is so obvious that it probably is
acceptable to do the obvious thing and not worry about code that depends
on that.
This does not affect tests that use a Reader of constant bytes (e.g. a
zeroReader) because shifting such a stream is a no-op. The stdlib uses
this internally (which is fine because it can be atomically updated if
the crypto libraries change).
It is possible that external tests could be doing the same and would
thus break if we ever, say, tweaked the way RSA key generation worked.
I feel that addressing that would be more effort than it's worth.
Fixes #21915
Change-Id: I84cff2e249acc921ad6eb5527171e02e6d39c530
Reviewed-on: https://go-review.googlesource.com/64451
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
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dev.boringcrypto
This is a git merge of master into dev.boringcrypto.
The branch was previously based on release-branch.go1.9,
so there are a handful of spurious conflicts that would
also arise if trying to merge master into release-branch.go1.9
(which we never do). Those have all been resolved by taking
the original file from master, discarding any Go 1.9-specific
edits.
all.bash passes on darwin/amd64, which is to say without
actually using BoringCrypto.
Go 1.10-related fixes to BoringCrypto itself will be in a followup CL.
This CL is just the merge.
Change-Id: I4c97711fec0fb86761913dcde28d25c001246c35
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The crypto.Signer interface takes pre-hased messages for ECDSA and RSA,
but the argument in the implementations was called “msg”, not “digest”,
which is confusing.
This change renames them to help clarify the intended use.
Change-Id: Ie2fb8753ca5280e493810d211c7c66223f94af88
Reviewed-on: https://go-review.googlesource.com/70950
Reviewed-by: Filippo Valsorda <hi@filippo.io>
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a -> an
Change-Id: I7362bdc199e83073a712be657f5d9ba16df3077e
Reviewed-on: https://go-review.googlesource.com/63850
Reviewed-by: Rob Pike <r@golang.org>
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Using atomic.Value causes vet errors in code copying
PublicKey or PrivateKey structures. I don't think the errors
are accurate, but it's easier to work around them than
to change vet or change atomic.Value.
See #21504.
Change-Id: I3a3435c1fc664cc5166c81674f6f7c58dab35f21
Reviewed-on: https://go-review.googlesource.com/56671
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
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Change-Id: I108e0a527bddd673b16582d206e0697341d0a0ea
Reviewed-on: https://go-review.googlesource.com/55478
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
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The code comment mixed up max and min. In this case, min is correct
because this entropy is only used to make the signature scheme
probabilistic. (I.e. if it were fixed then the scheme would still be
secure except that key.Sign(foo) would always give the same result for a
fixed key and foo.)
For this purpose, 256-bits is plenty.
Fixes #16819.
Change-Id: I309bb312b775cf0c4b7463c980ba4b19ad412c36
Reviewed-on: https://go-review.googlesource.com/30153
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Change-Id: I2b7a81cb809d109f10d5f0db957c614f466d6bfd
Reviewed-on: https://go-review.googlesource.com/24582
Reviewed-by: Adam Langley <agl@golang.org>
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The fact that crypto/ecdsa.Verify didn't reject negative inputs was a
mistake on my part: I had unsigned numbers on the brain. However, it
doesn't generally cause problems. (ModInverse results in zero, which
results in x being zero, which is rejected.)
The amd64 P-256 code will crash when given a large, negative input.
This fixes both crypto/ecdsa to reject these values and also the P-256
code to ignore the sign of inputs.
Change-Id: I6370ed7ca8125e53225866f55b616a4022b818f8
Reviewed-on: https://go-review.googlesource.com/22093
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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Change-Id: Ia6ed49d5ef3a256a55e6d4eaa1b4d9f0fc447013
Reviewed-on: https://go-review.googlesource.com/21560
Reviewed-by: Robert Griesemer <gri@golang.org>
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Named returned values should only be used on public funcs and methods
when it contributes to the documentation.
Named return values should not be used if they're only saving the
programmer a few lines of code inside the body of the function,
especially if that means there's stutter in the documentation or it
was only there so the programmer could use a naked return
statement. (Naked returns should not be used except in very small
functions)
This change is a manual audit & cleanup of public func signatures.
Signatures were not changed if:
* the func was private (wouldn't be in public godoc)
* the documentation referenced it
* the named return value was an interesting name. (i.e. it wasn't
simply stutter, repeating the name of the type)
There should be no changes in behavior. (At least: none intended)
Change-Id: I3472ef49619678fe786e5e0994bdf2d9de76d109
Reviewed-on: https://go-review.googlesource.com/20024
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
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This is based on the implementation used in OpenSSL, from a
submission by Shay Gueron and myself. Besides using assembly,
this implementation employs several optimizations described in:
S.Gueron and V.Krasnov, "Fast prime field elliptic-curve
cryptography with 256-bit primes"
In addition a new and improved modular inverse modulo N is
implemented here.
The performance measured on a Haswell based Macbook Pro shows 21X
speedup for the sign and 9X for the verify operations.
The operation BaseMult is 30X faster (and the Diffie-Hellman/ECDSA
key generation that use it are sped up as well).
The adaptation to Go with the help of Filippo Valsorda
Updated the submission for faster verify/ecdh, fixed some asm syntax
and API problems and added benchmarks.
Change-Id: I86a33636747d5c92f15e0c8344caa2e7e07e0028
Reviewed-on: https://go-review.googlesource.com/8968
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
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Updated the document URL in comments to avoid dead link
Old: http://www.secg.org/download/aid-780/sec1-v2.pdf
New: http://www.secg.org/sec1-v2.pdf
Change-Id: If13d0da4c0e7831b2bd92c45116c2412a2a965f5
Reviewed-on: https://go-review.googlesource.com/11550
Reviewed-by: Russ Cox <rsc@golang.org>
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crypto/rand.Reader doesn't ensure that short reads don't happen. This
change contains a couple of fixups where io.ReadFull wasn't being used
with it.
Change-Id: I3855b81f5890f2e703112eeea804aeba07b6a6b8
Reviewed-on: https://go-review.googlesource.com/7645
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
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ECDSA is unsafe to use if an entropy source produces predictable
output for the ephemeral nonces. E.g., [Nguyen]. A simple
countermeasure is to hash the secret key, the message, and
entropy together to seed a CSPRNG, from which the ephemeral key
is derived.
Fixes #9452
--
This is a minimalist (in terms of patch size) solution, though
not the most parsimonious in its use of primitives:
- csprng_key = ChopMD-256(SHA2-512(priv.D||entropy||hash))
- reader = AES-256-CTR(k=csprng_key)
This, however, provides at most 128-bit collision-resistance,
so that Adv will have a term related to the number of messages
signed that is significantly worse than plain ECDSA. This does
not seem to be of any practical importance.
ChopMD-256(SHA2-512(x)) is used, rather than SHA2-256(x), for
two sets of reasons:
*Practical:* SHA2-512 has a larger state and 16 more rounds; it
is likely non-generically stronger than SHA2-256. And, AFAIK,
cryptanalysis backs this up. (E.g., [Biryukov] gives a
distinguisher on 47-round SHA2-256 with cost < 2^85.) This is
well below a reasonable security-strength target.
*Theoretical:* [Coron] and [Chang] show that Chop-MD(F(x)) is
indifferentiable from a random oracle for slightly beyond the
birthday barrier. It seems likely that this makes a generic
security proof that this construction remains UF-CMA is
possible in the indifferentiability framework.
--
Many thanks to Payman Mohassel for reviewing this construction;
any mistakes are mine, however. And, as he notes, reusing the
private key in this way means that the generic-group (non-RO)
proof of ECDSA's security given in [Brown] no longer directly
applies.
--
[Brown]: http://www.cacr.math.uwaterloo.ca/techreports/2000/corr2000-54.ps
"Brown. The exact security of ECDSA. 2000"
[Coron]: https://www.cs.nyu.edu/~puniya/papers/merkle.pdf
"Coron et al. Merkle-Damgard revisited. 2005"
[Chang]: https://www.iacr.org/archive/fse2008/50860436/50860436.pdf
"Chang and Nandi. Improved indifferentiability security analysis
of chopMD hash function. 2008"
[Biryukov]: http://www.iacr.org/archive/asiacrypt2011/70730269/70730269.pdf
"Biryukov et al. Second-order differential collisions for reduced
SHA-256. 2011"
[Nguyen]: ftp://ftp.di.ens.fr/pub/users/pnguyen/PubECDSA.ps
"Nguyen and Shparlinski. The insecurity of the elliptic curve
digital signature algorithm with partially known nonces. 2003"
New tests:
TestNonceSafety: Check that signatures are safe even with a
broken entropy source.
TestINDCCA: Check that signatures remain non-deterministic
with a functional entropy source.
Updated "golden" KATs in crypto/tls/testdata that use ECDSA suites.
Change-Id: I55337a2fbec2e42a36ce719bd2184793682d678a
Reviewed-on: https://go-review.googlesource.com/3340
Reviewed-by: Adam Langley <agl@golang.org>
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This reverts commit 8d7bf2291b095d3a2ecaa2609e1101be46d80deb.
Change-Id: Iad2c74a504d64bcf7ca707b00bda29bc796a2ae9
Reviewed-on: https://go-review.googlesource.com/3320
Reviewed-by: Adam Langley <agl@golang.org>
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|
ECDSA is unsafe to use if an entropy source produces predictable
output for the ephemeral nonces. E.g., [Nguyen]. A simple
countermeasure is to hash the secret key, the message, and
entropy together to seed a CSPRNG, from which the ephemeral key
is derived.
--
This is a minimalist (in terms of patch size) solution, though
not the most parsimonious in its use of primitives:
- csprng_key = ChopMD-256(SHA2-512(priv.D||entropy||hash))
- reader = AES-256-CTR(k=csprng_key)
This, however, provides at most 128-bit collision-resistance,
so that Adv will have a term related to the number of messages
signed that is significantly worse than plain ECDSA. This does
not seem to be of any practical importance.
ChopMD-256(SHA2-512(x)) is used, rather than SHA2-256(x), for
two sets of reasons:
*Practical:* SHA2-512 has a larger state and 16 more rounds; it
is likely non-generically stronger than SHA2-256. And, AFAIK,
cryptanalysis backs this up. (E.g., [Biryukov] gives a
distinguisher on 47-round SHA2-256 with cost < 2^85.) This is
well below a reasonable security-strength target.
*Theoretical:* [Coron] and [Chang] show that Chop-MD(F(x)) is
indifferentiable from a random oracle for slightly beyond the
birthday barrier. It seems likely that this makes a generic
security proof that this construction remains UF-CMA is
possible in the indifferentiability framework.
--
Many thanks to Payman Mohassel for reviewing this construction;
any mistakes are mine, however. And, as he notes, reusing the
private key in this way means that the generic-group (non-RO)
proof of ECDSA's security given in [Brown] no longer directly
applies.
--
[Brown]: http://www.cacr.math.uwaterloo.ca/techreports/2000/corr2000-54.ps
"Brown. The exact security of ECDSA. 2000"
[Coron]: https://www.cs.nyu.edu/~puniya/papers/merkle.pdf
"Coron et al. Merkle-Damgard revisited. 2005"
[Chang]: https://www.iacr.org/archive/fse2008/50860436/50860436.pdf
"Chang and Nandi. Improved indifferentiability security analysis
of chopMD hash function. 2008"
[Biryukov]: http://www.iacr.org/archive/asiacrypt2011/70730269/70730269.pdf
"Biryukov et al. Second-order differential collisions for reduced
SHA-256. 2011"
[Nguyen]: ftp://ftp.di.ens.fr/pub/users/pnguyen/PubECDSA.ps
"Nguyen and Shparlinski. The insecurity of the elliptic curve
digital signature algorithm with partially known nonces. 2003"
Fixes #9452
Tests:
TestNonceSafety: Check that signatures are safe even with a
broken entropy source.
TestINDCCA: Check that signatures remain non-deterministic
with a functional entropy source.
Change-Id: Ie7e04057a3a26e6becb80e845ecb5004bb482745
Reviewed-on: https://go-review.googlesource.com/2422
Reviewed-by: Adam Langley <agl@golang.org>
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Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.
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