Ed25519 Signature verification in HSE

cij45 — Thu, 22 Jan 2026 17:45:01 GMT

Hello,

I am currently using the S32K312.

I imported a Ed25519 public key in the HSE and am attempting to verify a signature that was generated externally. However, the verification consistently returns the error code 0x55A5A164UL.

Could you please let me know if there is any issue with the parameters I am using for the Ed25519 verification service?

* If possible, I would also appreciate it if you could share a demo code or reference example for performing Ed25519 signature verification using the HSE on S32K312.

Thank you for your support!

const uint8_t eccPubKey[32] = {Ed25519 public key}; ImportEccKeyReq(NVM_ECC_SECUREBOOT_HANDLE, HSE_KEY_TYPE_ECC_PUB, HSE_KF_USAGE_VERIFY | HSE_KF_USAGE_AUTHORIZATION, HSE_EC_25519_ED25519, 256, (HOST_ADDR)eccPubKey, NULL); uint8_t demo_plain[16]= {input value not hashed }; uint8_t rsignature[32]= {First 32 signature}; uint8_t ssignature[32]= {Last 32 signature}; uint32_t demo_sigsize[1] = {32}; EddsaVerify(NVM_ECC_SECUREBOOT_HANDLE, FALSE, 16, (uint8_t*)demo_plain, FALSE, 0, 0, demo_sigsize, rsignature, demo_sigsize, ssignature);

hseSrvResponse_t EddsaVerify(hseKeyHandle_t keyHandle, bool_t bHashEddsa, uint32_t inputLength, const uint8_t* pInput, bool_t bInputIsHashed, uint8_t userContextLength, const uint8_t* pUserContext, const uint32_t* pRLen, const uint8_t* pR, const uint32_t* pSLen, const uint8_t* pS) { hseSignScheme_t signScheme; signScheme.signSch = HSE_SIGN_EDDSA; signScheme.sch.eddsa.bHashEddsa = bHashEddsa; signScheme.sch.eddsa.contextLength = userContextLength; signScheme.sch.eddsa.pContext = (HOST_ADDR)pUserContext; return VerReq(HSE_ACCESS_MODE_ONE_PASS, signScheme, keyHandle, muIf, muChannelIdx, inputLength, pInput, bInputIsHashed, 0, pRLen, pR, pSLen, pS, gSyncTxOption); } static hseSrvResponse_t VerReq(hseAccessMode_t accessMode, hseSignScheme_t signScheme, hseKeyHandle_t keyHandle, const uint8_t muIf, const uint8_t muChannelIdx, uint32_t inputLength, const uint8_t* pInput, bool_t bInputIsHashed, hseSGTOption_t sgtOption, const uint32_t* pSignatureLength0, const uint8_t* pSignature0, const uint32_t* pSignatureLength1, const uint8_t* pSignature1, hseTxOptions_t txOptions) { hseSrvDescriptor_t* pHseSrvDesc = &gHseSrvDesc[muIf][muChannelIdx]; hseSignSrv_t* pSignSrv; memset(pHseSrvDesc, 0, sizeof(hseSrvDescriptor_t)); pHseSrvDesc->srvId = HSE_SRV_ID_SIGN; pSignSrv = &(pHseSrvDesc->hseSrv.signReq); pSignSrv->accessMode = accessMode; pSignSrv->signScheme = signScheme; pSignSrv->authDir = HSE_AUTH_DIR_VERIFY; pSignSrv->keyHandle = keyHandle; pSignSrv->inputLength = inputLength; pSignSrv->pInput = (HOST_ADDR)pInput; pSignSrv->bInputIsHashed = bInputIsHashed; pSignSrv->sgtOption = sgtOption; pSignSrv->pSignature[0] = (HOST_ADDR)pSignature0; // R pSignSrv->pSignatureLength[0] = (HOST_ADDR)pSignatureLength0; // R len pSignSrv->pSignature[1] = (HOST_ADDR)pSignature1; // S pSignSrv->pSignatureLength[1] = (HOST_ADDR)pSignatureLength1; // S len return _HSE_Send(muIf, muChannelIdx, txOptions, pHseSrvDesc); }

Re: Ed25519 Signature verification in HSE

lukaszadrapa — Fri, 23 Jan 2026 11:58:34 GMT

It’s caused by endianness, most likely. There’s a note in HSE Firmware reference manual rev. 2.7 on page 118 that keys on Ed29919 curve are processed by conversion to little-endian bit strings. But HSE expects the keys in big-endian format. It’s necessary to swap the keys and also the signature.

You can use function like this for keys and for the signature:

void SwapArrayBytes

(

uint8_t *pu8Source,

uint32_t u32ByteLen

)

{

uint32_t u32Start = (uint32_t)0U;

uint32_t u32End = u32ByteLen - 1U ;

uint8_t u8Temp = (uint8_t)0U;

if ((NULL_PTR != pu8Source) && ((uint32_t)0U != u32ByteLen))

{

while (u32Start < u32End)

{

u8Temp = pu8Source[u32Start];

pu8Source[u32Start] = pu8Source[u32End];

pu8Source[u32End] = u8Temp;

u32Start++;

u32End--;

}

To test the result, you can use test vectors:

https://asecuritysite.com/ecc/eddsa4

Regards,

Lukas

Re: Ed25519 Signature verification in HSE

cij45 — Mon, 26 Jan 2026 16:27:16 GMT

That was the key point,
Thank you very much for your support!!

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