如何解决Java：Base64使用键对字符串进行编码
| 嗨，我有数据和键（两个字符串）。需要使用Base64使用密钥对数据进行编码。可以给我一个示例代码吗？解决方法
Base64不适用于“用密钥编码”。它只是一种编码方案：您可以使用Base64加密和解密字符串，而无需任何额外的操作。它仅用于（非常）基本的安全用法。
, 您可以使用密钥对数据进行异或，然后对它进行base64编码。
var key = \"mykey\";
var mydata = \"some long text here\";
var output = \'\';
for (var i = 0,len = mydata.length; i < len; i++) {
output += String.fromCharCode(mydata.charCodeAt(i) ^ key.charCodeAt(i % key.length));
}
const
C_ALPHABIG = \'ABCDEFGHIJKLMNOPQRSTUVWXYZ\';
C_ALPHASMALL = \'abcdefghijklmnopqrstuvwxyz\';
C_ALPHA = C_ALPHABIG+C_ALPHASMALL;
C_DIGITS = \'0123456789\';
C_SYMBOLS = \'+/\';
C_ALPHABET = C_ALPHA+C_DIGITS+C_SYMBOLS;
type
TIndexShiftDirection = (isdLeft,isdRight);
Function ShiftSymbolIndex(const AIndex: integer; const AKey: string; var ACurrentKeyPos: integer; const ADirection: TIndexShiftDirection): integer;
begin
Result := AIndex; if(AKey=\'\')then exit;
if(ACurrentKeyPosLength(AKey))then ACurrentKeyPos := 1;
if(ADirection=isdRight)
then begin
Result := Result+Ord(AKey[ACurrentKeyPos]);
if(Result>64)then Result := Result mod 64;
if(Result=0)then Result :=64;
end
else begin
Result := Result-Ord(AKey[ACurrentKeyPos]);
if(Result=Length(AKey))
then ACurrentKeyPos := 1
else inc(ACurrentKeyPos);
end;
Function Encode64(const s: string; const Key: string): string;
var
i,n,p,k : integer;
a,b,c,d : byte;
begin
Result := \'\'; k := 1; if(s=\'\')then exit;
n := Length(s)div 3;
if(n>0)then for i:=0 to n-1 do
begin
p := (i*3)+1;
a := (ord(s[p])shr 2); inc(a);
b := ((ord(s[p])and %00000011)shl 4)+(ord(s[p+1])shr 4); inc(b);
c := ((ord(s[p+1])and %00001111)shl 2)+(ord(s[p+2])shr 6); inc(c);
d := ord(s[p+2])and %00111111; inc(d);
//
a := ShiftSymbolIndex(a,key,k,isdRight);
b := ShiftSymbolIndex(b,isdRight);
c := ShiftSymbolIndex(c,isdRight);
d := ShiftSymbolIndex(d,isdRight);
//
Result := Result
+ C_ALPHABET[a]
+ C_ALPHABET[b]
+ C_ALPHABET[c]
+ C_ALPHABET[d];
end;
n := Length(s)-(n*3);
if(n=0)then begin {Result := Result+\'0\';} exit; end;
case n of
1: begin
p := Length(s);
a := (ord(s[p])shr 2); inc(a); a := ShiftSymbolIndex(a,isdRight);
b := (ord(s[p])and %00000011); inc(b); b := ShiftSymbolIndex(b,isdRight);
Result := Result
+ C_ALPHABET[a]
+ C_ALPHABET[b]
{+ \'2\'};//if Length(endoced_str)mod 4 = 2,then this case is true
end;
2: begin
p := Length(s)-1;
a := (ord(s[p])shr 2);
b := ((ord(s[p])and %00000011)shl 4)+(ord(s[p+1])shr 4);
c := (ord(s[p+1])and %00001111);
inc(a); a := ShiftSymbolIndex(a,isdRight);
inc(b); b := ShiftSymbolIndex(b,isdRight);
inc(c); c := ShiftSymbolIndex(c,isdRight);
Result := Result
+ C_ALPHABET[a]
+ C_ALPHABET[b]
+ C_ALPHABET[c]
{+ \'4\'};//if Length(endoced_str)mod 4 = 3,then this case is true
end;
end;
end;
Function Decode64(const s: string; const Key: string): string;
var
n,i,d : byte;
begin
Result := \'\'; k:=1; if(s=\'\')then exit;
n := Length(s)div 4;
if(n>0)then for i:=0 to n-1 do
begin
p := (i*4)+1;
a := Pos(s[p],C_ALPHABET); a := ShiftSymbolIndex(a,isdLeft);
b := Pos(s[p+1],C_ALPHABET); b := ShiftSymbolIndex(b,isdLeft);
c := Pos(s[p+2],C_ALPHABET); c := ShiftSymbolIndex(c,isdLeft);
d := Pos(s[p+3],C_ALPHABET); d := ShiftSymbolIndex(d,isdLeft);
if(a*b*c*d=0)then begin Result := \'\'; exit; end; //cannot be,if symbols are valid
Result := Result
+ chr(((a-1)shl 2) + ((b-1)shr 4))
+ chr((((b-1)and %001111)shl 4) + ((c-1)shr 2))
+ chr((((c-1)and %000011)shl 6) + (d-1));
end;
n := Length(s)mod 4;
if(n=0)then exit;
case n of
2: begin
p := Length(s)-1;
a := Pos(s[p],isdLeft);
b := Pos(s[p+1],isdLeft);
if(a*b=0)then begin Result := \'\'; exit; end; //cannot be,if symbols are valid
Result := Result
+ chr(((a-1)shl 2) + (b-1));
end;
3: begin
p := Length(s)-2;
a := Pos(s[p],C_ALPHABET);
b := Pos(s[p+1],C_ALPHABET);
c := Pos(s[p+2],C_ALPHABET);
if(a*b*c=0)
then begin Result := \'\'; exit; end; //cannot be,if symbols are valid
a := ShiftSymbolIndex(a,isdLeft);
b := ShiftSymbolIndex(b,isdLeft);
c := ShiftSymbolIndex(c,isdLeft);
Result := Result
+ chr(((a-1)shl 2) + ((b-1)shr 4))
+ chr((((b-1)and %001111)shl 4) + (c-1));
end;
else Result := \'\';
end;
end;
Base64
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