NSS (Network Security Services)

Facts and the checks behind them

Nothing below is copied from documentation. The check content/libraries/verify/nss/run.sh ran NSS (Network Security Services) 3.124 in the container image alpine:3.24.2 on October 20, 2026; the page must match what it printed, and each fact lists those lines.

• ECDSA signature encoding

  der-or-raw

  SEC_SignData returned strict DER; PK11_Sign returned 64 bytes of raw r‖s on P-256.

  Recorded by the check

  fact ecdsa-signature-encoding = der-or-raw
  evidence ecdsa-signature-encoding: SEC_SignData output parses as strict DER: yes; PK11_Sign: 64 bytes (P-256 raw r||s is 64)

• ECDSA nonce

  random

  Two SEC_SignData signatures of one message were different.

  Recorded by the check

  fact ecdsa-nonce = random
  evidence ecdsa-nonce: two SEC_SignData signatures of one message are different

• Low-S when signing

  either

  s is not normalized: high-S values appeared among 64 signatures.

  Recorded by the check

  fact ecdsa-low-s-sign = either
  evidence ecdsa-low-s-sign: signatures with s > n/2 among 64: yes

• High-S when verifying

  accepts-high-s

  A DER signature with s replaced by n − s verified with VFY_VerifyData.

  Recorded by the check

  fact ecdsa-low-s-verify = accepts-high-s

• What the signing call hashes

  hashes-message-or-digest

  SEC_SignData hashes the message; PK11_Sign over SHA-256 of the message produced a signature that VFY_VerifyData accepted.

  Recorded by the check

  fact ecdsa-prehash = hashes-message-or-digest
  evidence ecdsa-prehash: SEC_SignData hashes the message; PK11_Sign over SHA-256(message) verified with VFY_VerifyData: yes

• Digest longer than the curve order

  truncated

  PK11_Sign accepted a 64-byte digest on P-256; the signature verified over its first 32 bytes.

  Recorded by the check

  fact ecdsa-long-input = truncated
  evidence ecdsa-long-input: PK11_Sign accepted a 64-byte digest; the signature verifies over its first 32 bytes: yes

• Hash bound to the curve

  none

  ECDSA with SHA-256 signed and verified on a P-384 key.

  Recorded by the check

  fact ecdsa-hash-curve-binding = none
  evidence ecdsa-hash-curve-binding: ECDSA with SHA-256 on a P-384 key: sign ok, verify ok

• Malformed ECDSA signature

  returns-error

  VFY_VerifyData failed with SEC_ERROR_BAD_DER for raw r‖s and for 3 bytes, and with SEC_ERROR_BAD_SIGNATURE for a wrong message.

  Recorded by the check

  fact ecdsa-malformed-signature = returns-error
  evidence ecdsa-malformed-signature: VFY_VerifyData returned SECFailure with: raw r||s SEC_ERROR_BAD_DER, 3 bytes SEC_ERROR_BAD_DER, wrong message SEC_ERROR_BAD_SIGNATURE

• ECDSA curves

  P-256P-384P-521

  P-256, P-384 and P-521; P-224 and secp256k1 key generation returned SEC_ERROR_INVALID_KEY.

  Recorded by the check

  fact ecdsa-curves = P-256, P-384, P-521
  evidence ecdsa-curves: P-224: key generation SEC_ERROR_INVALID_KEY
  evidence ecdsa-curves: secp256k1: key generation SEC_ERROR_INVALID_KEY

• EdDSA

  Ed25519

  Ed25519 signed, verified and produced identical signatures twice; Ed448 key generation returned SEC_ERROR_INVALID_KEY.

  Recorded by the check

  fact eddsa = Ed25519
  evidence eddsa: Ed25519: keygen ok, sign and verify ok, deterministic yes
  evidence eddsa: Ed448 (OID 1.3.101.113): SEC_ERROR_INVALID_KEY

• Post-quantum algorithms

  ML-KEM

  ML-KEM-768 encapsulation round-tripped with a 1088-byte ciphertext; ML-DSA-65 key generation returned SEC_ERROR_INVALID_ALGORITHM, and SLH-DSA is not offered by the softoken.

  Recorded by the check

  fact pqc = ML-KEM
  evidence pqc: ML-KEM-768: ciphertext 1088 bytes, shared secrets match: yes
  evidence pqc: ML-DSA-65 key generation failed: SEC_ERROR_INVALID_ALGORITHM; CKM_ML_DSA_KEY_PAIR_GEN in the internal slot: no
  evidence pqc: CKM_SLH_DSA in the internal slot: no

Usage

#include <cryptohi.h>
#include <keyhi.h>
#include <nss.h>
#include <pk11pub.h>
#include <secoid.h>
#include <stdio.h>
#include <string.h>

int main(void) {
    NSS_NoDB_Init(NULL);
    /* EC key generation takes the curve OID, DER-encoded, as its parameter. */
    SECOidData *curve = SECOID_FindOIDByTag(SEC_OID_ANSIX962_EC_PRIME256V1);
    unsigned char oid[18] = {0x06, (unsigned char)curve->oid.len};
    memcpy(oid + 2, curve->oid.data, curve->oid.len);
    SECItem params = {siBuffer, oid, curve->oid.len + 2};
    PK11SlotInfo *slot = PK11_GetInternalSlot();
    SECKEYPublicKey *pub = NULL;
    SECKEYPrivateKey *priv = PK11_GenerateKeyPair(slot, CKM_EC_KEY_PAIR_GEN, &params, &pub, PR_FALSE, PR_FALSE, NULL);

    /* SEC_SignData hashes the message and returns DER; PK11_Sign would return raw r||s over a digest. */
    unsigned char msg[] = "order #1042 approved";
    SECItem sig = {siBuffer, NULL, 0};
    SEC_SignData(&sig, msg, sizeof msg - 1, priv, SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE);
    SECStatus rv = VFY_VerifyData(msg, sizeof msg - 1, pub, &sig, SEC_OID_ANSIX962_ECDSA_SHA256_SIGNATURE, NULL);
    printf("DER tag: 0x%02x, verified: %s\n", sig.data[0], rv == SECSuccess ? "yes" : "no");

    SECITEM_FreeItem(&sig, PR_FALSE);
    SECKEY_DestroyPrivateKey(priv);
    SECKEY_DestroyPublicKey(pub);
    PK11_FreeSlot(slot);
    return NSS_Shutdown() == SECSuccess ? 0 : 1;
}