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#️⃣ Hash Output Length

Look up the output length (bytes and bits) of common hash algorithms (MD5, SHA family) for hash value storage planning.

算法系数 1=MD5 2=SHA1 3=SHA256 4=SHA512

输出进制 16=十六进制 64=Base64

MD5=128bit, SHA1=160bit, SHA256=256bit, SHA512=512bit
Hex 长度 = 字节数 × 2

用于预估哈希值存储空间。

📚 深度解析：哈希输出长度

示例：SHA-256

输出 256 bit = 32 字节 = 64 个十六进制字符。

Item	Formula / Rule	Source / Standard
Digest length	Fixed per algorithm: MD5 128 bits, SHA-1 160, SHA-256 256, SHA-512 512	FIPS 180-4 Secure Hash Standard / RFC 1321
Serialized length	Hex length = bits / 4; Base64 length = 4 × ⌈(bits/8) / 3⌉	RFC 4648 §4 / ISO/IEC 10118-3
Collision bound	A collision is expected near 2^n/2 trials by the birthday bound, with n the digest bits	NIST SP 800-107 Rev.1 §4 Hash function security