b58_enc(Bits) ->
NBits = bit_size(Bits),
<<BitNum:NBits>> = Bits,
b58_enc(BitNum, []).
b58_enc(0, Acc) ->
lists:map(fun b58_int2char/1, Acc);
b58_enc(BitNum, Acc) ->
Q = BitNum div 58,
R = BitNum rem 58,
b58_enc(Q, [R | Acc]).
b58_dec(Str) ->
Ns = lists:map(fun b58_char2int/1, Str),
b58_dec(Ns, 0).
b58_dec([N | Ns], Acc) ->
NewAcc = (Acc*58) + N,
b58_dec(Ns, NewAcc);
b58_dec([], FinalAccN) ->
MinNBits = trunc(math:log2(FinalAccN) + 1),
NBytes = ceil(MinNBits / 8),
NBits = NBytes * 8,
<<FinalAccN:NBits>>.
b64_enc(<<A:6, B:6, C:6, D:6, Rest/binary>>) ->
CA = b64_int2char(A),
CB = b64_int2char(B),
CC = b64_int2char(C),
CD = b64_int2char(D),
[CA, CB, CC, CD | b64_enc(Rest)],
b64_enc(<<A:6, B:6, C:4>>) ->
CA = b64_int2char(A),
CB = b64_int2char(B),
CC = b64_int2char(C bsl 2),
[CA, CB, CC, $=];
b64_enc(<<A:6, B:2>>) ->
CA = b64_int2char(A),
CB = b64_int2char(B bsl 4),
[CA, CB, $=, $=];
b64_enc(<<>>) ->
[].
b64_dec(Base64_String) ->
b64_dec(Base64_String, <<>>).
b64_dec([W, X, $=, $=], Acc) ->
NW = b64_char2int(W),
NX = b64_char2int(X),
<<LastByte:8, 0:4>> = <<NW:6, NX:6>>,
<<Acc/binary, LastByte:8>>;
b64_dec([W, X, Y, $=], Acc) ->
NW = b64_char2int(W),
NX = b64_char2int(X),
NY = b64_char2int(Y),
<<B1:8, B2:8, 0:2>> = <<NW:6, NX:6, NY:6>>,
<<Acc/binary, B1:8, B2:8>>;
b64_dec([], Acc) ->
Acc;
b64_dec([W, X, Y, Z | Rest], Acc) ->
NW = b64_char2int(W),
NX = b64_char2int(X),
NY = b64_char2int(Y),
NZ = b64_char2int(Z),
NewAcc = <<Acc/binary, NW:6, NX:6, NY:6, NZ:6>>,
b64_dec(Rest, NewAcc).
