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Diffstat (limited to 'src/common/crypto_ed25519.c')
| -rw-r--r-- | src/common/crypto_ed25519.c | 609 |
1 files changed, 609 insertions, 0 deletions
diff --git a/src/common/crypto_ed25519.c b/src/common/crypto_ed25519.c new file mode 100644 index 0000000000..ea2d8e3892 --- /dev/null +++ b/src/common/crypto_ed25519.c @@ -0,0 +1,609 @@ +/* Copyright (c) 2013-2016, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file crypto_ed25519.c + * + * \brief Wrapper code for an ed25519 implementation. + */ + +#include "orconfig.h" +#ifdef HAVE_SYS_STAT_H +#include <sys/stat.h> +#endif + +#include "crypto.h" + +#include "crypto_curve25519.h" +#include "crypto_ed25519.h" +#include "crypto_format.h" +#include "torlog.h" +#include "util.h" + +#include "ed25519/ref10/ed25519_ref10.h" +#include "ed25519/donna/ed25519_donna_tor.h" + +#include <openssl/sha.h> + +static void pick_ed25519_impl(void); +static int ed25519_impl_spot_check(void); + +/** An Ed25519 implementation */ +typedef struct { + int (*selftest)(void); + + int (*seckey)(unsigned char *); + int (*seckey_expand)(unsigned char *, const unsigned char *); + int (*pubkey)(unsigned char *, const unsigned char *); + int (*keygen)(unsigned char *, unsigned char *); + + int (*open)(const unsigned char *, const unsigned char *, size_t, const + unsigned char *); + int (*sign)(unsigned char *, const unsigned char *, size_t, + const unsigned char *, const unsigned char *); + int (*open_batch)(const unsigned char **, size_t *, const unsigned char **, + const unsigned char **, size_t, int *); + + int (*blind_secret_key)(unsigned char *, const unsigned char *, + const unsigned char *); + int (*blind_public_key)(unsigned char *, const unsigned char *, + const unsigned char *); + + int (*pubkey_from_curve25519_pubkey)(unsigned char *, const unsigned char *, + int); +} ed25519_impl_t; + +static const ed25519_impl_t impl_ref10 = { + NULL, + + ed25519_ref10_seckey, + ed25519_ref10_seckey_expand, + ed25519_ref10_pubkey, + ed25519_ref10_keygen, + + ed25519_ref10_open, + ed25519_ref10_sign, + NULL, + + ed25519_ref10_blind_secret_key, + ed25519_ref10_blind_public_key, + + ed25519_ref10_pubkey_from_curve25519_pubkey, +}; + +static const ed25519_impl_t impl_donna = { + ed25519_donna_selftest, + + ed25519_donna_seckey, + ed25519_donna_seckey_expand, + ed25519_donna_pubkey, + ed25519_donna_keygen, + + ed25519_donna_open, + ed25519_donna_sign, + ed25519_sign_open_batch_donna, + + ed25519_donna_blind_secret_key, + ed25519_donna_blind_public_key, + + ed25519_donna_pubkey_from_curve25519_pubkey, +}; + +static const ed25519_impl_t *ed25519_impl = NULL; + +static inline const ed25519_impl_t * +get_ed_impl(void) +{ + if (PREDICT_UNLIKELY(ed25519_impl == NULL)) { + pick_ed25519_impl(); + } + return ed25519_impl; +} + +#ifdef TOR_UNIT_TESTS +static const ed25519_impl_t *saved_ed25519_impl = NULL; +void +crypto_ed25519_testing_force_impl(const char *name) +{ + tor_assert(saved_ed25519_impl == NULL); + saved_ed25519_impl = ed25519_impl; + if (! strcmp(name, "donna")) { + ed25519_impl = &impl_donna; + } else { + tor_assert(!strcmp(name, "ref10")); + ed25519_impl = &impl_ref10; + } +} +void +crypto_ed25519_testing_restore_impl(void) +{ + ed25519_impl = saved_ed25519_impl; + saved_ed25519_impl = NULL; +} +#endif + +/** + * Initialize a new ed25519 secret key in <b>seckey_out</b>. If + * <b>extra_strong</b>, take the RNG inputs directly from the operating + * system. Return 0 on success, -1 on failure. + */ +int +ed25519_secret_key_generate(ed25519_secret_key_t *seckey_out, + int extra_strong) +{ + int r; + uint8_t seed[32]; + if (extra_strong) + crypto_strongest_rand(seed, sizeof(seed)); + else + crypto_rand((char*)seed, sizeof(seed)); + + r = get_ed_impl()->seckey_expand(seckey_out->seckey, seed); + memwipe(seed, 0, sizeof(seed)); + + return r < 0 ? -1 : 0; +} + +/** + * Given a 32-byte random seed in <b>seed</b>, expand it into an ed25519 + * secret key in <b>seckey_out</b>. Return 0 on success, -1 on failure. + */ +int +ed25519_secret_key_from_seed(ed25519_secret_key_t *seckey_out, + const uint8_t *seed) +{ + if (get_ed_impl()->seckey_expand(seckey_out->seckey, seed) < 0) + return -1; + return 0; +} + +/** + * Given a secret key in <b>seckey</b>, expand it into an + * ed25519 public key. Return 0 on success, -1 on failure. + */ +int +ed25519_public_key_generate(ed25519_public_key_t *pubkey_out, + const ed25519_secret_key_t *seckey) +{ + if (get_ed_impl()->pubkey(pubkey_out->pubkey, seckey->seckey) < 0) + return -1; + return 0; +} + +/** Generate a new ed25519 keypair in <b>keypair_out</b>. If + * <b>extra_strong</b> is set, try to mix some system entropy into the key + * generation process. Return 0 on success, -1 on failure. */ +int +ed25519_keypair_generate(ed25519_keypair_t *keypair_out, int extra_strong) +{ + if (ed25519_secret_key_generate(&keypair_out->seckey, extra_strong) < 0) + return -1; + if (ed25519_public_key_generate(&keypair_out->pubkey, + &keypair_out->seckey)<0) + return -1; + return 0; +} + +/** + * Set <b>signature_out</b> to a signature of the <b>len</b>-byte message + * <b>msg</b>, using the secret and public key in <b>keypair</b>. + */ +int +ed25519_sign(ed25519_signature_t *signature_out, + const uint8_t *msg, size_t len, + const ed25519_keypair_t *keypair) +{ + if (get_ed_impl()->sign(signature_out->sig, msg, len, + keypair->seckey.seckey, + keypair->pubkey.pubkey) < 0) { + return -1; + } + + return 0; +} + +/** + * Check whether if <b>signature</b> is a valid signature for the + * <b>len</b>-byte message in <b>msg</b> made with the key <b>pubkey</b>. + * + * Return 0 if the signature is valid; -1 if it isn't. + */ +int +ed25519_checksig(const ed25519_signature_t *signature, + const uint8_t *msg, size_t len, + const ed25519_public_key_t *pubkey) +{ + return + get_ed_impl()->open(signature->sig, msg, len, pubkey->pubkey) < 0 ? -1 : 0; +} + +/** Validate every signature among those in <b>checkable</b>, which contains + * exactly <b>n_checkable</b> elements. If <b>okay_out</b> is non-NULL, set + * the i'th element of <b>okay_out</b> to 1 if the i'th element of + * <b>checkable</b> is valid, and to 0 otherwise. Return 0 if every signature + * was valid. Otherwise return -N, where N is the number of invalid + * signatures. + */ +int +ed25519_checksig_batch(int *okay_out, + const ed25519_checkable_t *checkable, + int n_checkable) +{ + int i, res; + const ed25519_impl_t *impl = get_ed_impl(); + + if (impl->open_batch == NULL) { + /* No batch verification implementation available, fake it by checking the + * each signature individually. + */ + res = 0; + for (i = 0; i < n_checkable; ++i) { + const ed25519_checkable_t *ch = &checkable[i]; + int r = ed25519_checksig(&ch->signature, ch->msg, ch->len, ch->pubkey); + if (r < 0) + --res; + if (okay_out) + okay_out[i] = (r == 0); + } + } else { + /* ed25519-donna style batch verification available. + * + * Theoretically, this should only be called if n_checkable >= 3, since + * that's the threshold where the batch verification actually kicks in, + * but the only difference is a few mallocs/frees. + */ + const uint8_t **ms; + size_t *lens; + const uint8_t **pks; + const uint8_t **sigs; + int *oks; + int all_ok; + + ms = tor_malloc(sizeof(uint8_t*)*n_checkable); + lens = tor_malloc(sizeof(size_t)*n_checkable); + pks = tor_malloc(sizeof(uint8_t*)*n_checkable); + sigs = tor_malloc(sizeof(uint8_t*)*n_checkable); + oks = okay_out ? okay_out : tor_malloc(sizeof(int)*n_checkable); + + for (i = 0; i < n_checkable; ++i) { + ms[i] = checkable[i].msg; + lens[i] = checkable[i].len; + pks[i] = checkable[i].pubkey->pubkey; + sigs[i] = checkable[i].signature.sig; + oks[i] = 0; + } + + res = 0; + all_ok = impl->open_batch(ms, lens, pks, sigs, n_checkable, oks); + for (i = 0; i < n_checkable; ++i) { + if (!oks[i]) + --res; + } + /* XXX: For now sanity check oks with the return value. Once we have + * more confidence in the code, if `all_ok == 0` we can skip iterating + * over oks since all the signatures were found to be valid. + */ + tor_assert(((res == 0) && !all_ok) || ((res < 0) && all_ok)); + + tor_free(ms); + tor_free(lens); + tor_free(pks); + tor_free(sigs); + if (! okay_out) + tor_free(oks); + } + + return res; +} + +/** + * Given a curve25519 keypair in <b>inp</b>, generate a corresponding + * ed25519 keypair in <b>out</b>, and set <b>signbit_out</b> to the + * sign bit of the X coordinate of the ed25519 key. + * + * NOTE THAT IT IS PROBABLY NOT SAFE TO USE THE GENERATED KEY FOR ANYTHING + * OUTSIDE OF WHAT'S PRESENTED IN PROPOSAL 228. In particular, it's probably + * not a great idea to use it to sign attacker-supplied anything. + */ +int +ed25519_keypair_from_curve25519_keypair(ed25519_keypair_t *out, + int *signbit_out, + const curve25519_keypair_t *inp) +{ + const char string[] = "Derive high part of ed25519 key from curve25519 key"; + ed25519_public_key_t pubkey_check; + SHA512_CTX ctx; + uint8_t sha512_output[64]; + + memcpy(out->seckey.seckey, inp->seckey.secret_key, 32); + SHA512_Init(&ctx); + SHA512_Update(&ctx, out->seckey.seckey, 32); + SHA512_Update(&ctx, string, sizeof(string)); + SHA512_Final(sha512_output, &ctx); + memcpy(out->seckey.seckey + 32, sha512_output, 32); + + ed25519_public_key_generate(&out->pubkey, &out->seckey); + + *signbit_out = out->pubkey.pubkey[31] >> 7; + + ed25519_public_key_from_curve25519_public_key(&pubkey_check, &inp->pubkey, + *signbit_out); + + tor_assert(fast_memeq(pubkey_check.pubkey, out->pubkey.pubkey, 32)); + + memwipe(&pubkey_check, 0, sizeof(pubkey_check)); + memwipe(&ctx, 0, sizeof(ctx)); + memwipe(sha512_output, 0, sizeof(sha512_output)); + + return 0; +} + +/** + * Given a curve25519 public key and sign bit of X coordinate of the ed25519 + * public key, generate the corresponding ed25519 public key. + */ +int +ed25519_public_key_from_curve25519_public_key(ed25519_public_key_t *pubkey, + const curve25519_public_key_t *pubkey_in, + int signbit) +{ + return get_ed_impl()->pubkey_from_curve25519_pubkey(pubkey->pubkey, + pubkey_in->public_key, + signbit); +} + +/** + * Given an ed25519 keypair in <b>inp</b>, generate a corresponding + * ed25519 keypair in <b>out</b>, blinded by the corresponding 32-byte input + * in 'param'. + * + * Tor uses key blinding for the "next-generation" hidden services design: + * service descriptors are encrypted with a key derived from the service's + * long-term public key, and then signed with (and stored at a position + * indexed by) a short-term key derived by blinding the long-term keys. + */ +int +ed25519_keypair_blind(ed25519_keypair_t *out, + const ed25519_keypair_t *inp, + const uint8_t *param) +{ + ed25519_public_key_t pubkey_check; + + get_ed_impl()->blind_secret_key(out->seckey.seckey, + inp->seckey.seckey, param); + + ed25519_public_blind(&pubkey_check, &inp->pubkey, param); + ed25519_public_key_generate(&out->pubkey, &out->seckey); + + tor_assert(fast_memeq(pubkey_check.pubkey, out->pubkey.pubkey, 32)); + + memwipe(&pubkey_check, 0, sizeof(pubkey_check)); + + return 0; +} + +/** + * Given an ed25519 public key in <b>inp</b>, generate a corresponding blinded + * public key in <b>out</b>, blinded with the 32-byte parameter in + * <b>param</b>. Return 0 on sucess, -1 on railure. + */ +int +ed25519_public_blind(ed25519_public_key_t *out, + const ed25519_public_key_t *inp, + const uint8_t *param) +{ + get_ed_impl()->blind_public_key(out->pubkey, inp->pubkey, param); + return 0; +} + +/** + * Store seckey unencrypted to <b>filename</b>, marking it with <b>tag</b>. + * Return 0 on success, -1 on failure. + */ +int +ed25519_seckey_write_to_file(const ed25519_secret_key_t *seckey, + const char *filename, + const char *tag) +{ + return crypto_write_tagged_contents_to_file(filename, + "ed25519v1-secret", + tag, + seckey->seckey, + sizeof(seckey->seckey)); +} + +/** + * Read seckey unencrypted from <b>filename</b>, storing it into + * <b>seckey_out</b>. Set *<b>tag_out</b> to the tag it was marked with. + * Return 0 on success, -1 on failure. + */ +int +ed25519_seckey_read_from_file(ed25519_secret_key_t *seckey_out, + char **tag_out, + const char *filename) +{ + ssize_t len; + + len = crypto_read_tagged_contents_from_file(filename, "ed25519v1-secret", + tag_out, seckey_out->seckey, + sizeof(seckey_out->seckey)); + if (len == sizeof(seckey_out->seckey)) { + return 0; + } else if (len >= 0) { + errno = EINVAL; + } + + return -1; +} + +/** + * Store pubkey unencrypted to <b>filename</b>, marking it with <b>tag</b>. + * Return 0 on success, -1 on failure. + */ +int +ed25519_pubkey_write_to_file(const ed25519_public_key_t *pubkey, + const char *filename, + const char *tag) +{ + return crypto_write_tagged_contents_to_file(filename, + "ed25519v1-public", + tag, + pubkey->pubkey, + sizeof(pubkey->pubkey)); +} + +/** + * Store pubkey unencrypted to <b>filename</b>, marking it with <b>tag</b>. + * Return 0 on success, -1 on failure. + */ +int +ed25519_pubkey_read_from_file(ed25519_public_key_t *pubkey_out, + char **tag_out, + const char *filename) +{ + ssize_t len; + + len = crypto_read_tagged_contents_from_file(filename, "ed25519v1-public", + tag_out, pubkey_out->pubkey, + sizeof(pubkey_out->pubkey)); + if (len == sizeof(pubkey_out->pubkey)) { + return 0; + } else if (len >= 0) { + errno = EINVAL; + } + + return -1; +} + +/** Release all storage held for <b>kp</b>. */ +void +ed25519_keypair_free(ed25519_keypair_t *kp) +{ + if (! kp) + return; + + memwipe(kp, 0, sizeof(*kp)); + tor_free(kp); +} + +/** Return true iff <b>key1</b> and <b>key2</b> are the same public key. */ +int +ed25519_pubkey_eq(const ed25519_public_key_t *key1, + const ed25519_public_key_t *key2) +{ + tor_assert(key1); + tor_assert(key2); + return tor_memeq(key1->pubkey, key2->pubkey, ED25519_PUBKEY_LEN); +} + +/** Check whether the given Ed25519 implementation seems to be working. + * If so, return 0; otherwise return -1. */ +static int +ed25519_impl_spot_check(void) +{ + static const uint8_t alicesk[32] = { + 0xc5,0xaa,0x8d,0xf4,0x3f,0x9f,0x83,0x7b, + 0xed,0xb7,0x44,0x2f,0x31,0xdc,0xb7,0xb1, + 0x66,0xd3,0x85,0x35,0x07,0x6f,0x09,0x4b, + 0x85,0xce,0x3a,0x2e,0x0b,0x44,0x58,0xf7 + }; + static const uint8_t alicepk[32] = { + 0xfc,0x51,0xcd,0x8e,0x62,0x18,0xa1,0xa3, + 0x8d,0xa4,0x7e,0xd0,0x02,0x30,0xf0,0x58, + 0x08,0x16,0xed,0x13,0xba,0x33,0x03,0xac, + 0x5d,0xeb,0x91,0x15,0x48,0x90,0x80,0x25 + }; + static const uint8_t alicemsg[2] = { 0xaf, 0x82 }; + static const uint8_t alicesig[64] = { + 0x62,0x91,0xd6,0x57,0xde,0xec,0x24,0x02, + 0x48,0x27,0xe6,0x9c,0x3a,0xbe,0x01,0xa3, + 0x0c,0xe5,0x48,0xa2,0x84,0x74,0x3a,0x44, + 0x5e,0x36,0x80,0xd7,0xdb,0x5a,0xc3,0xac, + 0x18,0xff,0x9b,0x53,0x8d,0x16,0xf2,0x90, + 0xae,0x67,0xf7,0x60,0x98,0x4d,0xc6,0x59, + 0x4a,0x7c,0x15,0xe9,0x71,0x6e,0xd2,0x8d, + 0xc0,0x27,0xbe,0xce,0xea,0x1e,0xc4,0x0a + }; + const ed25519_impl_t *impl = get_ed_impl(); + uint8_t sk[ED25519_SECKEY_LEN]; + uint8_t pk[ED25519_PUBKEY_LEN]; + uint8_t sig[ED25519_SIG_LEN]; + int r = 0; + + /* Some implementations (eg: The modified Ed25519-donna) have handy self-test + * code that sanity-checks the internals. If present, use that to screen out + * catastrophic errors like massive compiler failure. + */ + if (impl->selftest && impl->selftest() != 0) + goto fail; + + /* Validate results versus known answer tests. People really should be + * running "make test" instead of relying on this, but it's better than + * nothing. + * + * Test vectors taken from "EdDSA & Ed25519 - 6. Test Vectors for Ed25519 + * (TEST3)" (draft-josefsson-eddsa-ed25519-03). + */ + + /* Key expansion, public key derivation. */ + if (impl->seckey_expand(sk, alicesk) < 0) + goto fail; + if (impl->pubkey(pk, sk) < 0) + goto fail; + if (fast_memneq(pk, alicepk, ED25519_PUBKEY_LEN)) + goto fail; + + /* Signing, verification. */ + if (impl->sign(sig, alicemsg, sizeof(alicemsg), sk, pk) < 0) + return -1; + if (fast_memneq(sig, alicesig, ED25519_SIG_LEN)) + return -1; + if (impl->open(sig, alicemsg, sizeof(alicemsg), pk) < 0) + return -1; + + /* XXX/yawning: Someone that's more paranoid than I am, can write "Assume + * ref0 is cannonical, and fuzz impl against it" if they want, but I doubt + * that will catch anything that the known answer tests won't. + */ + goto end; + + fail: + r = -1; + end: + return r; +} + +/** Force the Ed25519 implementation to a given one, without sanity checking + * the output. Used for testing. + */ +void +ed25519_set_impl_params(int use_donna) +{ + if (use_donna) + ed25519_impl = &impl_donna; + else + ed25519_impl = &impl_ref10; +} + +/** Choose whether to use the Ed25519-donna implementation. */ +static void +pick_ed25519_impl(void) +{ + ed25519_impl = &impl_donna; + + if (ed25519_impl_spot_check() == 0) + return; + + log_warn(LD_CRYPTO, "The Ed25519-donna implementation seems broken; using " + "the ref10 implementation."); + ed25519_impl = &impl_ref10; +} + +/* Initialize the Ed25519 implementation. This is neccessary if you're + * going to use them in a multithreaded setting, and not otherwise. */ +void +ed25519_init(void) +{ + pick_ed25519_impl(); +} + |