diff options
| -rw-r--r-- | crypto/asymmetric_keys/public_key.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index e314fd57e6f8..3474fb34ded9 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -234,6 +234,7 @@ static int software_key_query(const struct kernel_pkey_params *params, info->key_size = len * 8; if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) { + int slen = len; /* * ECDSA key sizes are much smaller than RSA, and thus could * operate on (hashed) inputs that are larger than key size. @@ -247,8 +248,19 @@ static int software_key_query(const struct kernel_pkey_params *params, * Verify takes ECDSA-Sig (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. */ - info->max_sig_size = 2 * (len + 3) + 2; + if (strcmp(pkey->pkey_algo, "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. + */ + info->max_sig_size = 1 + (slen >= 128) + 1 + slen; } else { info->max_data_size = len; info->max_sig_size = len; |