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Merge pull request #65 from multiformats/feat/base36_spec
Base36 byte-encoding specification
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Diff for: ‎README.md

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@@ -8,7 +8,7 @@
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> Self identifying base encodings
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Multibase is a protocol for disambiguating the encoding of base-encoded (e.g.,
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base32, base64, base58, etc.) binary appearing in text.
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base32, base36, base64, base58, etc.) binary appearing in text.
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When text is encoded as bytes, we can usually use a one-size-fits-all encoding
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(UTF-8) because we're always encoding to the same set of 256 bytes (+/- the NUL
@@ -63,17 +63,19 @@ base8, 7, octal,
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base10, 9, decimal, draft
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base16, f, hexadecimal, default
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base16upper, F, hexadecimal, default
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base32hex, v, rfc4648 no padding - highest char, candidate
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base32hexupper, V, rfc4648 no padding - highest char, candidate
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base32hexpad, t, rfc4648 with padding, candidate
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base32hexpadupper, T, rfc4648 with padding, candidate
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base32, b, rfc4648 no padding, default
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base32upper, B, rfc4648 no padding, default
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base32pad, c, rfc4648 with padding, candidate
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base32padupper, C, rfc4648 with padding, candidate
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base32hex, v, rfc4648 case-insensitive - no padding - highest char, candidate
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base32hexupper, V, rfc4648 case-insensitive - no padding - highest char, candidate
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base32hexpad, t, rfc4648 case-insensitive - with padding, candidate
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base32hexpadupper, T, rfc4648 case-insensitive - with padding, candidate
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base32, b, rfc4648 case-insensitive - no padding, default
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base32upper, B, rfc4648 case-insensitive - no padding, default
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base32pad, c, rfc4648 case-insensitive - with padding, candidate
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base32padupper, C, rfc4648 case-insensitive - with padding, candidate
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base32z, h, z-base-32 (used by Tahoe-LAFS), draft
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base58flickr, Z, base58 flicker, candidate
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base36, k, base36 [0-9a-z] case-insensitive - no padding, draft
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base36upper, K, base36 [0-9a-z] case-insensitive - no padding, draft
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base58btc, z, base58 bitcoin, default
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base58flickr, Z, base58 flicker, candidate
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base64, m, rfc4648 no padding, default
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base64pad, M, rfc4648 with padding - MIME encoding, candidate
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base64url, u, rfc4648 no padding, default
@@ -107,6 +109,7 @@ Consider the following encodings of the same binary string:
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```
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4D756C74696261736520697320617765736F6D6521205C6F2F # base16 (hex)
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JV2WY5DJMJQXGZJANFZSAYLXMVZW63LFEEQFY3ZP # base32
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3IY8QKL64VUGCX009XWUHKF6GBBTS3TVRXFRA5R # base36
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YAjKoNbau5KiqmHPmSxYCvn66dA1vLmwbt # base58
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TXVsdGliYXNlIGlzIGF3ZXNvbWUhIFxvLw== # base64
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```
@@ -116,11 +119,12 @@ And consider the same encodings with their multibase prefix
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```
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F4D756C74696261736520697320617765736F6D6521205C6F2F # base16 F
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BJV2WY5DJMJQXGZJANFZSAYLXMVZW63LFEEQFY3ZP # base32 B
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K3IY8QKL64VUGCX009XWUHKF6GBBTS3TVRXFRA5R # base36 K
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zYAjKoNbau5KiqmHPmSxYCvn66dA1vLmwbt # base58 z
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MTXVsdGliYXNlIGlzIGF3ZXNvbWUhIFxvLw== # base64 M
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```
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The base prefixes used are: `F, B, z, M`.
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The base prefixes used are: `F, B, K, z, M`.
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## FAQ

Diff for: ‎multibase.csv

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@@ -5,17 +5,19 @@ base8, 7, octal,
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base10, 9, decimal, draft
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base16, f, hexadecimal, default
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base16upper, F, hexadecimal, default
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base32hex, v, rfc4648 no padding - highest char, candidate
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base32hexupper, V, rfc4648 no padding - highest char, candidate
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base32hexpad, t, rfc4648 with padding, candidate
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base32hexpadupper, T, rfc4648 with padding, candidate
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base32, b, rfc4648 no padding, default
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base32upper, B, rfc4648 no padding, default
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base32pad, c, rfc4648 with padding, candidate
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base32padupper, C, rfc4648 with padding, candidate
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base32hex, v, rfc4648 case-insensitive - no padding - highest char, candidate
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base32hexupper, V, rfc4648 case-insensitive - no padding - highest char, candidate
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base32hexpad, t, rfc4648 case-insensitive - with padding, candidate
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base32hexpadupper, T, rfc4648 case-insensitive - with padding, candidate
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base32, b, rfc4648 case-insensitive - no padding, default
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base32upper, B, rfc4648 case-insensitive - no padding, default
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base32pad, c, rfc4648 case-insensitive - with padding, candidate
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base32padupper, C, rfc4648 case-insensitive - with padding, candidate
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base32z, h, z-base-32 (used by Tahoe-LAFS), draft
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base58flickr, Z, base58 flicker, candidate
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base36, k, base36 [0-9a-z] case-insensitive - no padding, draft
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base36upper, K, base36 [0-9a-z] case-insensitive - no padding, draft
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base58btc, z, base58 bitcoin, default
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base58flickr, Z, base58 flicker, candidate
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base64, m, rfc4648 no padding, default
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base64pad, M, rfc4648 with padding - MIME encoding, candidate
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base64url, u, rfc4648 no padding, default

Diff for: ‎rfcs/Base36.md

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# Base36
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The multibase base36 prefix is the character `k` or `K`. The digit-alphabet
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consists of 0..9 and then the case insensitive range a..z for the values 10..35
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## Encoding
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A byte array is encoded to base36 by:
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1. Counting the number of leading 0 bytes (Z).
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2. Interpreting the rest of the byte array as a big-endian unsigned integer (N).
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3. Concatenating a length Z string of '0' characters with the base36
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representation of N.
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A byte array is encoded to multibase base36 by prefixing its base36 encoding
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with the character `k`.
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## Decoding
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A multibase base36 encoded string is decoded by first dropping the multibase
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prefix (which must be `k` or `K`).
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The remaining characters are then converted to a byte array by:
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1. Counting the number of leading '0' characters (Z).
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2. Interpreting the rest of the character sequence as a base36 unsigned integer
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(N).
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3. Concatenating a length Z array of NULL (0x00) bytes with N encoded as a
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big-endian unsigned integer.
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## Examples
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Byte Array <-> Base36 Multibase:
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| Bytes | == | LC Base36 | OR | UC Base36 |
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|---|---|---|---|---|
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| `[0x00, 0x01]` | == | `"k01"` | | `"K01"` |
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| `[0x00, 0x00, 0xff]` | == | `"k0073"` | | `"K0073"` |
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| `[0x01, 0x00]` | == | `"k74"` | | `"K74"` |
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| `[0x00, 0x01, 0x00]` | == | `"k074"` | | `"K074"` |

Diff for: ‎tests/test1.csv

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@@ -13,6 +13,8 @@ base32padupper, "CIRSWGZLOORZGC3DJPJSSAZLWMVZHS5DINFXGOIJB"
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base32hexpad, "t8him6pbeehp62r39f9ii0pbmclp7it38d5n6e891"
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base32hexpadupper, "T8HIM6PBEEHP62R39F9II0PBMCLP7IT38D5N6E891"
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base32z, "het1sg3mqqt3gn5djxj11y3msci3817depfzgqejb"
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base36, "k343ixo7d49hqj1ium15pgy1wzww5fxrid21td7l"
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base36upper, "K343IXO7D49HQJ1IUM15PGY1WZWW5FXRID21TD7L"
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base58flickr, "Ztwe7gVTeK8wswS1gf8hrgAua9fcw9reboD"
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base58btc, "zUXE7GvtEk8XTXs1GF8HSGbVA9FCX9SEBPe"
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base64, "mRGVjZW50cmFsaXplIGV2ZXJ5dGhpbmchIQ"

Diff for: ‎tests/test2.csv

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@@ -13,6 +13,8 @@ base32padupper, "CPFSXGIDNMFXGSIBB"
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base32hexpad, "tf5in683dc5n6i811"
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base32hexpadupper, "TF5IN683DC5N6I811"
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base32z, "hxf1zgedpcfzg1ebb"
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base36, "k2lcpzo5yikidynfl"
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base36upper, "K2LCPZO5YIKIDYNFL"
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base58flickr, "Z7Pznk19XTTzBtx"
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base58btc, "z7paNL19xttacUY"
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base64, "meWVzIG1hbmkgIQ"

Diff for: ‎tests/test3.csv

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@@ -13,6 +13,8 @@ base32padupper, "CNBSWY3DPEB3W64TMMQ======"
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base32hexpad, "td1imor3f41rmusjccg======"
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base32hexpadupper, "TD1IMOR3F41RMUSJCCG======"
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base32z, "hpb1sa5dxrb5s6hucco"
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base36, "kfuvrsivvnfrbjwajo"
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base36upper, "KFUVRSIVVNFRBJWAJO"
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base58flickr, "ZrTu1dk6cWsRYjYu"
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base58btc, "zStV1DL6CwTryKyV"
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base64, "maGVsbG8gd29ybGQ"

Diff for: ‎tests/test4.csv

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@@ -13,6 +13,8 @@ base32padupper, "CAB4WK4ZANVQW42JAEE======"
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base32hexpad, "t01smasp0dlgmsq9044======"
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base32hexpadupper, "T01SMASP0DLGMSQ9044======"
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base32z, "hybhskh3ypiosh4jyrr"
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base36, "k02lcpzo5yikidynfl"
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base36upper, "K02LCPZO5YIKIDYNFL"
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base58flickr, "Z17Pznk19XTTzBtx"
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base58btc, "z17paNL19xttacUY"
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base64, "mAHllcyBtYW5pICE"

Diff for: ‎tests/test5.csv

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@@ -13,6 +13,8 @@ base32padupper, "CAAAHSZLTEBWWC3TJEAQQ===="
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base32hexpad, "t0007ipbj41mm2rj940gg===="
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base32hexpadupper, "T0007IPBJ41MM2RJ940GG===="
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base32z, "hyyy813murbssn5ujryoo"
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base36, "k002lcpzo5yikidynfl"
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base36upper, "K002LCPZO5YIKIDYNFL"
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base58flickr, "Z117Pznk19XTTzBtx"
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base58btc, "z117paNL19xttacUY"
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base64, "mAAB5ZXMgbWFuaSAh"

Diff for: ‎tests/test6.csv

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@@ -9,3 +9,5 @@ base32pad, "cnbswy3dpeB3W64TMMQ======"
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base32padupper, "Cnbswy3dpeB3W64TMMQ======"
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base32hexpad, "td1imor3f41RMUSJCCG======"
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base32hexpadupper, "Td1imor3f41RMUSJCCG======"
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base36, "kfUvrsIvVnfRbjWaJo"
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base36upper, "KfUVrSIVVnFRbJWAJo"

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