github.com/CommerciumBlockchain/go-commercium@v0.0.0-20220709212705-b46438a77516/crypto/fixed/fixed.go (about)

     1  package fixed
     2  
     3  // LegacyKeccak20 calculates the LegacyKeccak256 hash of data
     4  func LegacyKeccak20(data [20]byte) [32]byte {
     5  	var a [25]uint64
     6  	// Pad and permute in one go
     7  	a[16] = 0x8000000000000000
     8  	a[2] = 1<<32 | uint64(data[19])<<24 | uint64(data[18])<<16 | uint64(data[17])<<8 | uint64(data[16])
     9  	a[1] = uint64(data[15])<<56 | uint64(data[14])<<48 | uint64(data[13])<<40 | uint64(data[12])<<32 |
    10  		uint64(data[11])<<24 | uint64(data[10])<<16 | uint64(data[9])<<8 | uint64(data[8])
    11  	a[0] = uint64(data[7])<<56 | uint64(data[6])<<48 | uint64(data[5])<<40 | uint64(data[4])<<32 |
    12  		uint64(data[3])<<24 | uint64(data[2])<<16 | uint64(data[1])<<8 | uint64(data[0])
    13  	// Hash it
    14  	keccakF1600(&a)
    15  	// Convert back to bytes, and return
    16  	var buf [32]byte
    17  	/*
    18  		It is possible (the golang lib version does it) to use an unaligned copy here,
    19  		but it is platform specific.
    20  		Since it's a pretty small slice we're dealing with, we're a generic method instead.
    21  		The 'cost' of using the generic version is ~5%, 454ns instead of 430ns.
    22  
    23  		ab := (*[136]uint8)(unsafe.Pointer(&a[0]))
    24  		copy(buf[:], ab[:])
    25  	*/
    26  	for i := 0; i < 4; i++ {
    27  		buf[8*i+7] = byte(a[i] >> 56)
    28  		buf[8*i+6] = byte(a[i] >> 48)
    29  		buf[8*i+5] = byte(a[i] >> 40)
    30  		buf[8*i+4] = byte(a[i] >> 32)
    31  		buf[8*i+3] = byte(a[i] >> 24)
    32  		buf[8*i+2] = byte(a[i] >> 16)
    33  		buf[8*i+1] = byte(a[i] >> 8)
    34  		buf[8*i] = byte(a[i])
    35  	}
    36  	return buf
    37  }
    38  
    39  // LegacyKeccak32 calculates the LegacyKeccak256 hash of data
    40  func LegacyKeccak32(data [32]byte) [32]byte {
    41  	var a [25]uint64
    42  	// Pad and permute in one go
    43  	a[16] = 0x8000000000000000
    44  	a[4] = 1
    45  	a[3] = uint64(data[31])<<56 | uint64(data[30])<<48 | uint64(data[29])<<40 | uint64(data[28])<<32 |
    46  		uint64(data[27])<<24 | uint64(data[26])<<16 | uint64(data[25])<<8 | uint64(data[24])
    47  	a[2] = uint64(data[23])<<56 | uint64(data[22])<<48 | uint64(data[21])<<40 | uint64(data[20])<<32 |
    48  		uint64(data[19])<<24 | uint64(data[18])<<16 | uint64(data[17])<<8 | uint64(data[16])
    49  	a[1] = uint64(data[15])<<56 | uint64(data[14])<<48 | uint64(data[13])<<40 | uint64(data[12])<<32 |
    50  		uint64(data[11])<<24 | uint64(data[10])<<16 | uint64(data[9])<<8 | uint64(data[8])
    51  	a[0] = uint64(data[7])<<56 | uint64(data[6])<<48 | uint64(data[5])<<40 | uint64(data[4])<<32 |
    52  		uint64(data[3])<<24 | uint64(data[2])<<16 | uint64(data[1])<<8 | uint64(data[0])
    53  	// Hash it
    54  	keccakF1600(&a)
    55  	// Convert back to bytes, and return
    56  	var buf [32]byte
    57  	/*
    58  		It is possible (the golang lib version does it) to use an unaligned copy here,
    59  		but it is platform specific.
    60  		Since it's a pretty small slice we're dealing with, we're a generic method instead.
    61  		The 'cost' of using the generic version is ~5%, 454ns instead of 430ns.
    62  
    63  		ab := (*[136]uint8)(unsafe.Pointer(&a[0]))
    64  		copy(buf[:], ab[:])
    65  	*/
    66  	for i := 0; i < 4; i++ {
    67  		buf[8*i+7] = byte(a[i] >> 56)
    68  		buf[8*i+6] = byte(a[i] >> 48)
    69  		buf[8*i+5] = byte(a[i] >> 40)
    70  		buf[8*i+4] = byte(a[i] >> 32)
    71  		buf[8*i+3] = byte(a[i] >> 24)
    72  		buf[8*i+2] = byte(a[i] >> 16)
    73  		buf[8*i+1] = byte(a[i] >> 8)
    74  		buf[8*i] = byte(a[i])
    75  	}
    76  	return buf
    77  }