SHAKE variants of the ECDSA signature algorithms appear to be using truncated digests.
We've found we can pass on demo by truncating SHAKE128 to 16 bytes and SHAKE256 to 32 bytes.
FIPS PUB 186-5 Section 6.4 states "An approved hash function or an XOF shall be used during the generation of digital signatures.
Approved XOFs are SHAKE128 and SHAKE256, which are specified in FIPS 202. When SHAKE128 or SHAKE256 is used as an XOF in Sections 6.4.1 and 6.4.2 below, its output length shall be 256 or 512 bits, respectively."
SHAKE variants of the ECDSA signature algorithms appear to be using truncated digests.
We've found we can pass on demo by truncating SHAKE128 to 16 bytes and SHAKE256 to 32 bytes.
FIPS PUB 186-5 Section 6.4 states "An approved hash function or an XOF shall be used during the generation of digital signatures.
Approved XOFs are SHAKE128 and SHAKE256, which are specified in FIPS 202. When SHAKE128 or SHAKE256 is used as an XOF in Sections 6.4.1 and 6.4.2 below, its output length shall be 256 or 512 bits, respectively."