delphi Base32 的加密和解密

const

ValidChars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567';

// Base32解码

function Base32Decode(const source: string): string;

var

UpperSource: string;

p, i, l, n, j: Integer;

begin

UpperSource := UpperCase(source);

l := Length(source);

n := 0;

j := 0;

Result := '';

for i := 1 to l do

begin

n := n shl 5; // Move buffer left by 5 to make room

p := Pos(UpperSource[i], ValidChars);

if p >= 0 then

n := n + (p - 1); // Add value into buffer

j := j + 5; // Keep track of number of bits in buffer

if (j >= 8) then

begin

j := j - 8;

Result := Result + chr((n and ($FF shl j)) shr j);

end;

// Base32编码

function Base32Encode(str: UTF8String): string;

var

B: Int64;

i, j, len: Integer;

begin

Result := '';

//每5个字符一组进行编码（5个字符x8=40位，5位*8字符=40位，BASE32每个字符用5位表示）

len := length(str);

while len > 0 do

begin

if len >= 5 then

len := 5;

//将这5个字符的ASCII码按顺序存放到Int64（共8个字节）整数中

B := 0;

for i := 1 to len do

B := B shl 8 + Ord(str[i]); //存放一个字符，左移一个字节（8位）

B := B shl ((8 - len) * 8); //最后再左移3个字节（3*8）

j := system.Math.ceil(len * 8 / 5);

//编码，每5位表示一个字符，8个字符刚好是40位

for i := 1 to 8 do

begin

if i <= j then

begin

Result := Result + ValidChars[B shr 59 + 1]; //右移7*8位+3位，从BASE32表中取字符

B := B shl 5; //每次左移5位

end

else

Result := Result + '=';

end;

//去掉已处理的5个字符

delete(str, 1, len);

len := length(str);

end;

————————————————

原文链接：https://blog.csdn.net/warrially/article/details/103146664

推荐分享