diff options
Diffstat (limited to 'crypto/ecdsa-x962.c')
| -rw-r--r-- | crypto/ecdsa-x962.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/crypto/ecdsa-x962.c b/crypto/ecdsa-x962.c index 8a15232dfa77..6a77c13e192b 100644 --- a/crypto/ecdsa-x962.c +++ b/crypto/ecdsa-x962.c @@ -99,6 +99,40 @@ static unsigned int ecdsa_x962_key_size(struct crypto_sig *tfm) return crypto_sig_keysize(ctx->child); } +static unsigned int ecdsa_x962_max_size(struct crypto_sig *tfm) +{ + struct ecdsa_x962_ctx *ctx = crypto_sig_ctx(tfm); + struct sig_alg *alg = crypto_sig_alg(ctx->child); + int slen = crypto_sig_keysize(ctx->child); + + /* + * Verify takes ECDSA-Sig-Value (described in RFC 5480) as input, + * which is actually 2 'key_size'-bit integers encoded in ASN.1. + * Account for the ASN.1 encoding overhead here. + * + * NIST P192/256/384 may prepend a '0' to a coordinate to indicate + * a positive integer. NIST P521 never needs it. + */ + if (strcmp(alg->base.cra_name, "ecdsa-nist-p521") != 0) + slen += 1; + + /* Length of encoding the x & y coordinates */ + slen = 2 * (slen + 2); + + /* + * If coordinate encoding takes at least 128 bytes then an + * additional byte for length encoding is needed. + */ + return 1 + (slen >= 128) + 1 + slen; +} + +static unsigned int ecdsa_x962_digest_size(struct crypto_sig *tfm) +{ + struct ecdsa_x962_ctx *ctx = crypto_sig_ctx(tfm); + + return crypto_sig_digestsize(ctx->child); +} + static int ecdsa_x962_set_pub_key(struct crypto_sig *tfm, const void *key, unsigned int keylen) { @@ -180,6 +214,8 @@ static int ecdsa_x962_create(struct crypto_template *tmpl, struct rtattr **tb) inst->alg.verify = ecdsa_x962_verify; inst->alg.key_size = ecdsa_x962_key_size; + inst->alg.max_size = ecdsa_x962_max_size; + inst->alg.digest_size = ecdsa_x962_digest_size; inst->alg.set_pub_key = ecdsa_x962_set_pub_key; inst->free = ecdsa_x962_free; |