1
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var parseKeys = require('parse-asn1')
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2
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var randomBytes = require('randombytes')
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3
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var createHash = require('create-hash')
|
4
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var mgf = require('./mgf')
|
5
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var xor = require('./xor')
|
6
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var BN = require('bn.js')
|
7
|
var withPublic = require('./withPublic')
|
8
|
var crt = require('browserify-rsa')
|
9
|
var Buffer = require('safe-buffer').Buffer
|
10
|
|
11
|
module.exports = function publicEncrypt (publicKey, msg, reverse) {
|
12
|
var padding
|
13
|
if (publicKey.padding) {
|
14
|
padding = publicKey.padding
|
15
|
} else if (reverse) {
|
16
|
padding = 1
|
17
|
} else {
|
18
|
padding = 4
|
19
|
}
|
20
|
var key = parseKeys(publicKey)
|
21
|
var paddedMsg
|
22
|
if (padding === 4) {
|
23
|
paddedMsg = oaep(key, msg)
|
24
|
} else if (padding === 1) {
|
25
|
paddedMsg = pkcs1(key, msg, reverse)
|
26
|
} else if (padding === 3) {
|
27
|
paddedMsg = new BN(msg)
|
28
|
if (paddedMsg.cmp(key.modulus) >= 0) {
|
29
|
throw new Error('data too long for modulus')
|
30
|
}
|
31
|
} else {
|
32
|
throw new Error('unknown padding')
|
33
|
}
|
34
|
if (reverse) {
|
35
|
return crt(paddedMsg, key)
|
36
|
} else {
|
37
|
return withPublic(paddedMsg, key)
|
38
|
}
|
39
|
}
|
40
|
|
41
|
function oaep (key, msg) {
|
42
|
var k = key.modulus.byteLength()
|
43
|
var mLen = msg.length
|
44
|
var iHash = createHash('sha1').update(Buffer.alloc(0)).digest()
|
45
|
var hLen = iHash.length
|
46
|
var hLen2 = 2 * hLen
|
47
|
if (mLen > k - hLen2 - 2) {
|
48
|
throw new Error('message too long')
|
49
|
}
|
50
|
var ps = Buffer.alloc(k - mLen - hLen2 - 2)
|
51
|
var dblen = k - hLen - 1
|
52
|
var seed = randomBytes(hLen)
|
53
|
var maskedDb = xor(Buffer.concat([iHash, ps, Buffer.alloc(1, 1), msg], dblen), mgf(seed, dblen))
|
54
|
var maskedSeed = xor(seed, mgf(maskedDb, hLen))
|
55
|
return new BN(Buffer.concat([Buffer.alloc(1), maskedSeed, maskedDb], k))
|
56
|
}
|
57
|
function pkcs1 (key, msg, reverse) {
|
58
|
var mLen = msg.length
|
59
|
var k = key.modulus.byteLength()
|
60
|
if (mLen > k - 11) {
|
61
|
throw new Error('message too long')
|
62
|
}
|
63
|
var ps
|
64
|
if (reverse) {
|
65
|
ps = Buffer.alloc(k - mLen - 3, 0xff)
|
66
|
} else {
|
67
|
ps = nonZero(k - mLen - 3)
|
68
|
}
|
69
|
return new BN(Buffer.concat([Buffer.from([0, reverse ? 1 : 2]), ps, Buffer.alloc(1), msg], k))
|
70
|
}
|
71
|
function nonZero (len) {
|
72
|
var out = Buffer.allocUnsafe(len)
|
73
|
var i = 0
|
74
|
var cache = randomBytes(len * 2)
|
75
|
var cur = 0
|
76
|
var num
|
77
|
while (i < len) {
|
78
|
if (cur === cache.length) {
|
79
|
cache = randomBytes(len * 2)
|
80
|
cur = 0
|
81
|
}
|
82
|
num = cache[cur++]
|
83
|
if (num) {
|
84
|
out[i++] = num
|
85
|
}
|
86
|
}
|
87
|
return out
|
88
|
}
|