question: public byte [ ] generate64BitHashId ( ) throws CryptoException { try { DERBitString publicKeyBitString = encodePublicKeyAsBitString ( publicKey ) ; byte [ ] hash = DigestUtil . getMessageDigest ( publicKeyBitString . getBytes ( ) , DigestType . SHA1 ) ; byte [ ] subHash = Arrays . copyOfRange ( hash , 12 , 20 ) ; subHash [ 0 ] &= 0x0F ; subHash [ 0 ] |= 0x40 ; return subHash ; } catch ( IOException ex ) { throw new CryptoException ( res . getString ( "NoGenerateKeyIdentifier.exception.message" ) , ex ) ; } }
target:  Generate 64 bit hash key identifier.