0009953: unexplained numeric constants in js_talercrypto_eddsa_sign

ID	Project	Category	View Status	Date Submitted	Last Update

0009953	Taler	qtart	public	2025-05-13 14:12	2025-05-13 14:39

Reporter	fefe	Assigned To	Florian Dold
Priority	normal	Severity	minor	Reproducibility	have not tried
Status	assigned	Resolution	open

Summary	0009953: unexplained numeric constants in js_talercrypto_eddsa_sign
Description	In tart_module.c: 595 unsigned char sk[crypto_sign_SECRETKEYBYTES]; 596 unsigned char pk[crypto_sign_PUBLICKEYBYTES]; 597 unsigned char sig[64]; Why 64? 605 seed = JS_GetArrayBuffer(ctx, &seed_size, argv[1]); 606 if (!seed) { 607 return JS_EXCEPTION; 608 } 609 if (seed_size != 32) { 610 return JS_ThrowTypeError(ctx, "invalid private key size"); 611 } Why 32? Also the error string is probably wrong because crypto_sign_SECRETKEYBYTES is 64 not 32. 617 res = crypto_sign_detached((uint8_t )sig, 618 NULL, 619 (uint8_t )data, 620 data_size, 621 sk); The second argument (NULL here) is supposed to return the size of the signature (always 64). 625 return make_js_ta_copy(ctx, sig, 64); This looks like it is meant to be algorithm agnostic (calls crypto_sign_detached instead of crypto_sign_ed25519_detached), but what if a future version of libsodium changes the algorithm and thus the sizes change too? Maybe better call the ed25519 function directly?
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Date Modified	Username	Field	Change
2025-05-13 14:12	fefe	New Issue
2025-05-13 14:39	Christian Grothoff	Assigned To	=> Florian Dold
2025-05-13 14:39	Christian Grothoff	Status	new => assigned