/**
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* ANSI X.923 padding strategy.
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*/
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export const AnsiX923 = {
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pad(data, blockSize) {
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const _data = data;
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// Shortcuts
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const dataSigBytes = _data.sigBytes;
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const blockSizeBytes = blockSize * 4;
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// Count padding bytes
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const nPaddingBytes = blockSizeBytes - (dataSigBytes % blockSizeBytes);
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// Compute last byte position
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const lastBytePos = dataSigBytes + nPaddingBytes - 1;
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// Pad
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_data.clamp();
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_data.words[lastBytePos >>> 2] |= nPaddingBytes << (24 - (lastBytePos % 4) * 8);
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_data.sigBytes += nPaddingBytes;
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},
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unpad(data) {
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const _data = data;
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// Get number of padding bytes from last byte
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const nPaddingBytes = _data.words[(_data.sigBytes - 1) >>> 2] & 0xff;
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// Remove padding
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_data.sigBytes -= nPaddingBytes;
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},
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};
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