From e93f4c21c59756604440ad8cbf27e67d29c99ffd Mon Sep 17 00:00:00 2001 From: NIIBE Yutaka Date: Thu, 6 Aug 2015 17:31:41 +0900 Subject: Add Curve25519 support. * cipher/ecc-curves.c (curve_aliases, domain_parms): Add Curve25519. * tests/curves.c (N_CURVES): It's 22 now. * src/cipher.h (PUBKEY_FLAG_DJB_TWEAK): New. * cipher/ecc-common.h (_gcry_ecc_mont_decodepoint): New. * cipher/ecc-misc.c (_gcry_ecc_mont_decodepoint): New. * cipher/ecc.c (nist_generate_key): Handle the case of PUBKEY_FLAG_DJB_TWEAK and Montgomery curve. (test_ecdh_only_keys, check_secret_key): Likewise. (ecc_generate): Support Curve25519 which is Montgomery curve with flag PUBKEY_FLAG_DJB_TWEAK and PUBKEY_FLAG_COMP. (ecc_encrypt_raw): Get flags from KEYPARMS and handle PUBKEY_FLAG_DJB_TWEAK and Montgomery curve. (ecc_decrypt_raw): Likewise. (compute_keygrip): Handle the case of PUBKEY_FLAG_DJB_TWEAK. * cipher/pubkey-util.c (_gcry_pk_util_parse_flaglist): PUBKEY_FLAG_EDDSA implies PUBKEY_FLAG_DJB_TWEAK. Parse "djb-tweak" for PUBKEY_FLAG_DJB_TWEAK. -- With PUBKEY_FLAG_DJB_TWEAK, secret key has msb set and it should be always multiple by cofactor. --- cipher/ecc-misc.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) (limited to 'cipher/ecc-misc.c') diff --git a/cipher/ecc-misc.c b/cipher/ecc-misc.c index 88266b55..2f2e5937 100644 --- a/cipher/ecc-misc.c +++ b/cipher/ecc-misc.c @@ -287,3 +287,51 @@ _gcry_ecc_compute_public (mpi_point_t Q, mpi_ec_t ec, return Q; } + + +gpg_err_code_t +_gcry_ecc_mont_decodepoint (gcry_mpi_t pk, mpi_ec_t ctx, mpi_point_t result) +{ + unsigned char *rawmpi; + unsigned int rawmpilen; + + if (mpi_is_opaque (pk)) + { + const unsigned char *buf; + unsigned char *p; + + buf = mpi_get_opaque (pk, &rawmpilen); + if (!buf) + return GPG_ERR_INV_OBJ; + rawmpilen = (rawmpilen + 7)/8; + + if (rawmpilen > 1 && (rawmpilen%2) && buf[0] == 0x40) + { + rawmpilen--; + buf++; + } + + rawmpi = xtrymalloc (rawmpilen? rawmpilen:1); + if (!rawmpi) + return gpg_err_code_from_syserror (); + + p = rawmpi + rawmpilen; + while (p > rawmpi) + *--p = *buf++; + } + else + { + /* Note: Without using an opaque MPI it is not reliable possible + to find out whether the public key has been given in + uncompressed format. Thus we expect native EdDSA format. */ + rawmpi = _gcry_mpi_get_buffer (pk, ctx->nbits/8, &rawmpilen, NULL); + if (!rawmpi) + return gpg_err_code_from_syserror (); + } + + _gcry_mpi_set_buffer (result->x, rawmpi, rawmpilen, 0); + xfree (rawmpi); + mpi_set_ui (result->z, 1); + + return 0; +} -- cgit v1.2.1