Implement ECDSA signing and verification for the nettle/hogweed backend, for the prime256v1 (NIST P-256) and secp384r1 (NIST P-384) curves. A public key (Qx || Qy) is loaded into an ecc_point for verify; a private key (the scalar d) into an ecc_scalar for sign, using nettle's ecdsa_sign() / ecdsa_verify().
The encrypt/decrypt driver ops return an error. Signed-off-by: Jamin Lin <[email protected]> --- crypto/akcipher-nettle.c.inc | 267 +++++++++++++++++++++++++++++++++++ 1 file changed, 267 insertions(+) diff --git a/crypto/akcipher-nettle.c.inc b/crypto/akcipher-nettle.c.inc index 1d4bd6960e..34bdc3de27 100644 --- a/crypto/akcipher-nettle.c.inc +++ b/crypto/akcipher-nettle.c.inc @@ -20,6 +20,10 @@ */ #include <nettle/rsa.h> +#include <nettle/ecdsa.h> +#include <nettle/ecc-curve.h> +#include <nettle/ecc.h> +#include <nettle/bignum.h> #include "qemu/osdep.h" #include "qemu/host-utils.h" @@ -55,6 +59,12 @@ static QCryptoAkCipher *qcrypto_nettle_rsa_new( const uint8_t *key, size_t keylen, Error **errp); +static QCryptoAkCipher *qcrypto_nettle_ecdsa_new( + const QCryptoAkCipherOptionsECDSA *opt, + QCryptoAkCipherKeyType type, + const uint8_t *key, size_t keylen, + Error **errp); + QCryptoAkCipher *qcrypto_akcipher_new(const QCryptoAkCipherOptions *opts, QCryptoAkCipherKeyType type, const uint8_t *key, size_t keylen, @@ -64,6 +74,10 @@ QCryptoAkCipher *qcrypto_akcipher_new(const QCryptoAkCipherOptions *opts, case QCRYPTO_AK_CIPHER_ALGO_RSA: return qcrypto_nettle_rsa_new(&opts->u.rsa, type, key, keylen, errp); + case QCRYPTO_AK_CIPHER_ALGO_ECDSA: + return qcrypto_nettle_ecdsa_new(&opts->u.ecdsa, type, key, keylen, + errp); + default: error_setg(errp, "Unsupported algorithm: %u", opts->alg); return NULL; @@ -422,6 +436,249 @@ error: } +/* + * ECDSA support (sign and verify) + * + * Keys and signatures use raw big-endian formats: + * - public key: Qx || Qy, each 'coord_len' bytes + * - private key: the scalar d, 'coord_len' bytes + * - signature: r || s, each 'coord_len' bytes + * - the input to sign/verify is a raw message digest + */ +typedef struct QCryptoNettleECDSA { + QCryptoAkCipher akcipher; + QCryptoAkCipherKeyType type; + struct ecc_point pub; + struct ecc_scalar priv; + QCryptoCurveID curve_id; +} QCryptoNettleECDSA; + +static const struct ecc_curve *qcrypto_nettle_ecdsa_curve( + QCryptoCurveID curve_id) +{ + switch (curve_id) { + case QCRYPTO_CURVE_ID_PRIME256V1: + return nettle_get_secp_256r1(); + + case QCRYPTO_CURVE_ID_SECP384R1: + return nettle_get_secp_384r1(); + + default: + return NULL; + } +} + +static size_t qcrypto_nettle_ecdsa_coord_len(QCryptoCurveID curve_id) +{ + switch (curve_id) { + case QCRYPTO_CURVE_ID_PRIME256V1: + return 32; + + case QCRYPTO_CURVE_ID_SECP384R1: + return 48; + + default: + return 0; + } +} + +static void qcrypto_nettle_ecdsa_free(QCryptoAkCipher *akcipher) +{ + QCryptoNettleECDSA *ecdsa = (QCryptoNettleECDSA *)akcipher; + if (!ecdsa) { + return; + } + + if (ecdsa->type == QCRYPTO_AK_CIPHER_KEY_TYPE_PRIVATE) { + ecc_scalar_clear(&ecdsa->priv); + } else { + ecc_point_clear(&ecdsa->pub); + } + g_free(ecdsa); +} + +static int qcrypto_nettle_ecdsa_encrypt(QCryptoAkCipher *akcipher, + const void *in, size_t in_len, + void *out, size_t out_len, + Error **errp) +{ + error_setg(errp, "ECDSA does not support encryption"); + return -1; +} + +static int qcrypto_nettle_ecdsa_decrypt(QCryptoAkCipher *akcipher, + const void *in, size_t in_len, + void *out, size_t out_len, + Error **errp) +{ + error_setg(errp, "ECDSA does not support decryption"); + return -1; +} + +static int qcrypto_nettle_ecdsa_sign(QCryptoAkCipher *akcipher, + const void *in, size_t in_len, + void *out, size_t out_len, + Error **errp) +{ + QCryptoNettleECDSA *ecdsa = (QCryptoNettleECDSA *)akcipher; + size_t coord_len = qcrypto_nettle_ecdsa_coord_len(ecdsa->curve_id); + struct dsa_signature sig; + + if (ecdsa->type != QCRYPTO_AK_CIPHER_KEY_TYPE_PRIVATE) { + error_setg(errp, "ECDSA sign requires a private key"); + return -1; + } + + if (in_len == 0 || in_len > akcipher->max_dgst_len) { + error_setg(errp, "Invalid digest length %zu", in_len); + return -1; + } + + if (out_len < coord_len * 2) { + error_setg(errp, "Signature buffer length %zu is less than %zu", + out_len, coord_len * 2); + return -1; + } + + dsa_signature_init(&sig); + ecdsa_sign(&ecdsa->priv, NULL, wrap_nettle_random_func, in_len, in, &sig); + + /* output is r || s, each zero-padded to the curve size */ + nettle_mpz_get_str_256(coord_len, out, sig.r); + nettle_mpz_get_str_256(coord_len, (uint8_t *)out + coord_len, sig.s); + + dsa_signature_clear(&sig); + return coord_len * 2; +} + +static int qcrypto_nettle_ecdsa_verify(QCryptoAkCipher *akcipher, + const void *in, size_t in_len, + const void *in2, size_t in2_len, + Error **errp) +{ + QCryptoNettleECDSA *ecdsa = (QCryptoNettleECDSA *)akcipher; + size_t coord_len = qcrypto_nettle_ecdsa_coord_len(ecdsa->curve_id); + struct dsa_signature sig; + int ret = -1; + + /* signature is r || s */ + if (in_len != coord_len * 2) { + error_setg(errp, "Signature length %zu is not %zu", + in_len, coord_len * 2); + return ret; + } + + if (in2_len == 0 || in2_len > akcipher->max_dgst_len) { + error_setg(errp, "Invalid digest length %zu", in2_len); + return ret; + } + + dsa_signature_init(&sig); + nettle_mpz_set_str_256_u(sig.r, coord_len, in); + nettle_mpz_set_str_256_u(sig.s, coord_len, (const uint8_t *)in + coord_len); + + if (ecdsa_verify(&ecdsa->pub, in2_len, in2, &sig) == 1) { + ret = 0; + } else { + error_setg(errp, "Failed to verify signature"); + } + + dsa_signature_clear(&sig); + return ret; +} + +QCryptoAkCipherDriver nettle_ecdsa = { + .encrypt = qcrypto_nettle_ecdsa_encrypt, + .decrypt = qcrypto_nettle_ecdsa_decrypt, + .sign = qcrypto_nettle_ecdsa_sign, + .verify = qcrypto_nettle_ecdsa_verify, + .free = qcrypto_nettle_ecdsa_free, +}; + +static QCryptoAkCipher *qcrypto_nettle_ecdsa_new( + const QCryptoAkCipherOptionsECDSA *opt, + QCryptoAkCipherKeyType type, + const uint8_t *key, size_t keylen, + Error **errp) +{ + QCryptoNettleECDSA *ecdsa; + const struct ecc_curve *curve = qcrypto_nettle_ecdsa_curve(opt->curve_id); + size_t coord_len = qcrypto_nettle_ecdsa_coord_len(opt->curve_id); + mpz_t x; + mpz_t y; + + if (!curve || coord_len == 0) { + error_setg(errp, "Unsupported curve id: %u", opt->curve_id); + return NULL; + } + + switch (type) { + case QCRYPTO_AK_CIPHER_KEY_TYPE_PUBLIC: + if (keylen != coord_len * 2) { + error_setg(errp, "Public key length %zu is not %zu", + keylen, coord_len * 2); + return NULL; + } + break; + + case QCRYPTO_AK_CIPHER_KEY_TYPE_PRIVATE: + if (keylen != coord_len) { + error_setg(errp, "Private key length %zu is not %zu", + keylen, coord_len); + return NULL; + } + break; + + default: + error_setg(errp, "Unknown akcipher key type %d", type); + return NULL; + } + + ecdsa = g_new0(QCryptoNettleECDSA, 1); + ecdsa->akcipher.driver = &nettle_ecdsa; + ecdsa->type = type; + ecdsa->curve_id = opt->curve_id; + ecdsa->akcipher.max_dgst_len = coord_len; + ecdsa->akcipher.max_signature_len = coord_len * 2; + + if (type == QCRYPTO_AK_CIPHER_KEY_TYPE_PUBLIC) { + /* public key: Qx || Qy */ + ecc_point_init(&ecdsa->pub, curve); + mpz_init(x); + mpz_init(y); + nettle_mpz_set_str_256_u(x, coord_len, key); + nettle_mpz_set_str_256_u(y, coord_len, + (const uint8_t *)key + coord_len); + + if (!ecc_point_set(&ecdsa->pub, x, y)) { + error_setg(errp, "Invalid ECDSA public key (not on curve)"); + mpz_clear(x); + mpz_clear(y); + qcrypto_nettle_ecdsa_free((QCryptoAkCipher *)ecdsa); + return NULL; + } + + mpz_clear(x); + mpz_clear(y); + } else { + /* private key: the scalar d */ + ecc_scalar_init(&ecdsa->priv, curve); + mpz_init(x); + nettle_mpz_set_str_256_u(x, coord_len, key); + + if (!ecc_scalar_set(&ecdsa->priv, x)) { + error_setg(errp, "Invalid ECDSA private key"); + mpz_clear(x); + qcrypto_nettle_ecdsa_free((QCryptoAkCipher *)ecdsa); + return NULL; + } + + mpz_clear(x); + } + + return (QCryptoAkCipher *)ecdsa; +} + bool qcrypto_akcipher_supports(QCryptoAkCipherOptions *opts) { switch (opts->alg) { @@ -445,6 +702,16 @@ bool qcrypto_akcipher_supports(QCryptoAkCipherOptions *opts) } break; + case QCRYPTO_AK_CIPHER_ALGO_ECDSA: + switch (opts->u.ecdsa.curve_id) { + case QCRYPTO_CURVE_ID_PRIME256V1: + case QCRYPTO_CURVE_ID_SECP384R1: + return true; + + default: + return false; + } + default: return false; } -- 2.53.0
