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| author | Paul Guyot <[email protected]> | 2014-05-15 16:29:34 +0200 |
|---|---|---|
| committer | Paul Guyot <[email protected]> | 2014-05-15 16:38:12 +0200 |
| commit | eee8d83ad1766b038b16102eb2006eaa7c21b4e5 (patch) | |
| tree | c8f7734ed17a3f1dab16be45c8b2215be60e897a /lib/crypto | |
| parent | 5ade234d37600ea80dbb309f431c615937ea253d (diff) | |
| download | otp-eee8d83ad1766b038b16102eb2006eaa7c21b4e5.tar.gz otp-eee8d83ad1766b038b16102eb2006eaa7c21b4e5.tar.bz2 otp-eee8d83ad1766b038b16102eb2006eaa7c21b4e5.zip | |
Fix bug in SRP implementation
SRP didn't work with smaller primes as user secret was improperly
computed.
Formula is: (B - (k * g^x)) ^ (a + (u * x)) % N
Previously, the code computed a + (u * x) % N instead of a + (u * x).
a typically is a 256 bits random number (RFC 5054 says it should be at
least 256 bits), u and x are SHA1 signatures (160 bits). So a + (u * x)
can differ from a + (u * x) % N for N primes smaller than 320 bits.
Diffstat (limited to 'lib/crypto')
| -rw-r--r-- | lib/crypto/c_src/crypto.c | 4 | ||||
| -rw-r--r-- | lib/crypto/test/crypto_SUITE.erl | 28 |
2 files changed, 29 insertions, 3 deletions
diff --git a/lib/crypto/c_src/crypto.c b/lib/crypto/c_src/crypto.c index 3020cadc56..a2868850d7 100644 --- a/lib/crypto/c_src/crypto.c +++ b/lib/crypto/c_src/crypto.c @@ -2892,8 +2892,8 @@ static ERL_NIF_TERM srp_user_secret_nif(ErlNifEnv* env, int argc, const ERL_NIF_ /* a + (u * x) */ bn_exp2 = BN_new(); - BN_mod_mul(bn_result, bn_u, bn_exponent, bn_prime, bn_ctx); - BN_mod_add(bn_exp2, bn_a, bn_result, bn_prime, bn_ctx); + BN_mul(bn_result, bn_u, bn_exponent, bn_ctx); + BN_add(bn_exp2, bn_a, bn_result); /* (B - (k * g^x)) ^ (a + (u * x)) % N */ BN_mod_exp(bn_result, bn_base, bn_exp2, bn_prime, bn_ctx); diff --git a/lib/crypto/test/crypto_SUITE.erl b/lib/crypto/test/crypto_SUITE.erl index 479c947029..03aa3964a5 100644 --- a/lib/crypto/test/crypto_SUITE.erl +++ b/lib/crypto/test/crypto_SUITE.erl @@ -690,7 +690,7 @@ group_config(ecdsa = Type, Config) -> SignVerify = [{Type, sha, Public, Private, Msg}], [{sign_verify, SignVerify} | Config]; group_config(srp, Config) -> - GenerateCompute = [srp3(), srp6(), srp6a()], + GenerateCompute = [srp3(), srp6(), srp6a(), srp6a_smaller_prime()], [{generate_compute, GenerateCompute} | Config]; group_config(ecdh, Config) -> Compute = ecdh(), @@ -1496,6 +1496,32 @@ srp6() -> ClientPublic = crypto:mod_pow(Generator, ClientPrivate, Prime), srp(ClientPrivate, Generator, Prime, Version, Verifier, ServerPublic, ServerPrivate, UserPassHash, Scrambler, SessionKey). + +srp6a_smaller_prime() -> + Username = <<"alice">>, + Password = <<"password123">>, + Salt = <<"mystrongsalt">>, + Prime = hexstr2bin("894B645E89E1535BBDAD5B8B290650530801B18EBFBF5E8FAB3C82872A3E9BB7"), + Generator = <<7>>, + Version = '6a', + Scrambler = hexstr2bin("18DE4A002AD05EF464B19AE2B6929F9B1319C7AA"), + Verifier = hexstr2bin("867401D5DE10964768184EAF246B322760C847604075FA66A4423907" + "8428BCA5"), + ClientPrivate = hexstr2bin("C49F832EE8D67ECF9E7F2785EB0622D8B3FE2344C00F96E1AEF4103C" + "A44D51F9"), + ServerPrivate = hexstr2bin("6C78CCEAAEC15E69068A87795B2A20ED7B45CFC5A254EBE2F17F144A" + "4D99DB18"), + ClientPublic = hexstr2bin("2452A57166BBBF690DB77539BAF9C57CD1ED99D5AA15ED925AD9B5C3" + "64BBEDFF"), + ServerPublic = hexstr2bin("2C0464DE84B91E4963A3546CAC0EFE55F31F49208C3F0AD7EE55F444" + "8F38BA7F"), + + SessionKey = hexstr2bin("65581B2302580BD26F522A5A421CF969B9CCBCE4051196B034A2A9D22065D848"), + UserPassHash = crypto:hash(sha, [Salt, crypto:hash(sha, [Username, <<$:>>, Password])]), + Verifier = crypto:mod_pow(Generator, UserPassHash, Prime), + ClientPublic = crypto:mod_pow(Generator, ClientPrivate, Prime), + srp(ClientPrivate, Generator, Prime, Version, Verifier, ServerPublic, ServerPrivate, UserPassHash, Scrambler, SessionKey). + srp6a() -> Username = <<"alice">>, Password = <<"password123">>, |