How to decrypt signatureCipher in Youtube?

Question

YouTube

There is data that my script pulls when loading the site:

{
    itag: 251,
    mimeType: 'audio/webm; codecs="opus"',
    bitrate: 155819,
    initRange: { start: '0', end: '258' },
    indexRange: { start: '259', end: '646' },
    lastModified: '1612778806311777',
    contentLength: '3646801',
    quality: 'tiny',
    projectionType: 'RECTANGULAR',
    averageBitrate: 131974,
    audioQuality: 'AUDIO_QUALITY_MEDIUM',
    approxDurationMs: '221061',
    audioSampleRate: '48000',
    audioChannels: 2,
    loudnessDb: 7,
    signatureCipher: 's=%3D%3DAhoWbZqY-2843x8F6qKlHLfVxs5Yup9NTAiU3bzKVfjAiA_nwULV9cRLC0kONl5-ctP5E0bDiZ-Z7jCiox__pxTPMAhIQRw8JQ0qOAOO&sp=sig&url=https://rr2---sn-4gxb5u-qo3s.googlevideo.com/videoplayback%3Fexpire%3D1639587183%26ei%3DD8m5YavPHdiE0u8PvdyJyAo%26ip%3DYOUR IP ADRESS%26id%3Do-ACE3MuYFbdkHPZ-Gm07EIIv_7ubSGMwDtXIzI3GLO_2u%26itag%3D251%26source%3Dyoutube%26requiressl%3Dyes%26mh%3D-W%26mm%3D31%252C29%26mn%3Dsn-4gxb5u-qo3s%252Csn-3c27snee%26ms%3Dau%252Crdu%26mv%3Dm%26mvi%3D2%26pl%3D23%26gcr%3Dua%26initcwndbps%3D1275000%26vprv%3D1%26mime%3Daudio%252Fwebm%26ns%3DVi6l9jzwaQEoquGhy7JykKAG%26gir%3Dyes%26clen%3D3646801%26dur%3D221.061%26lmt%3D1612778806311777%26mt%3D1639564625%26fvip%3D16%26keepalive%3Dyes%26fexp%3D24001373%252C24007246%26c%3DWEB%26txp%3D2311222%26n%3D3jKJ-DJVG38lL-6sD%26sparams%3Dexpire%252Cei%252Cip%252Cid%252Citag%252Csource%252Crequiressl%252Cgcr%252Cvprv%252Cmime%252Cns%252Cgir%252Cclen%252Cdur%252Clmt%26lsparams%3Dmh%252Cmm%252Cmn%252Cms%252Cmv%252Cmvi%252Cpl%252Cinitcwndbps%26lsig%3DAG3C_xAwRgIhAJpczLmLMTlDtESdmwvIEalJnjaCCJ4Kk3ZuSntnan4XAiEA7o-AgaMECfMjQ1vklqAkPzFbJFRXt0gb1HOMmthgSSs%253D'
  }

Here we can observe the signatureCipher , which, when decrypted correctly, gives access to the video\audio itself with a link:
HTTPS:r2---sn-4gxb5u-qo3s.googlevideo.com/videoplayback?expire=1639587276&ei=bMm5Yc_ILJW07QS9776oBQ&ip= YOUR IP ADRESS& id = o-ANCvSN1cAL0rsQMVyuIl6525gtX7nBY9YJaLcl6_z8h_ & itag = 251 & source = youtube & requiressl = yes & mh = -W & mm = 31% 2C29 & mn = sn-4gxb5u -qo3s% 2Csn-3c27snee & ms = au% 2Crdu & mv = m & mvi = 2 & pl = 23 & gcr = ua & initcwndbps = 1,215,000 & vprv = 1 & mime = audio% 2Fwebm & ns = ogFSH9l3mpOE7RrgJwkYdyEG & gir = yes & clen = 3646801 & dur = 221.061 & lmt = 1612778806311777 & mt = 1639565351 & fvip = 16 & keepalive = yes & fexp = 24,001,373% 2C24007246 & c = WEB & txp = 2311222 & n = PlCx-QIv5h0_yw & sparams = expire% 2Cei% 2Cip% 2Cid% 2Citag% 2Csource% 2Crequiressl% 2Cgcr% 2Cvprv% 2Cmime% 2Cns% 2Cgir% 2Cclen% 2Cdur% 2Clmt &

lsparams = mh% 2Cmm% 2Cmn% 2Cms% 2Cmv% 2Cmvi% 2Cpl% 2Cinitcwndbps & lsig = AG3C_xAwRQIgdHC2nW_-es0GELusA_5PSpjysViBmClvYiAPtnVtDYkCIQCBJUtz9lcvjDsKAGXzA28GREOkm54R-nyxcpv76xg02Q% 3D% 3D & alr = yes &sig=AOq0QJ8wRAIgWniXNRBol5Qs3kbhp5B6D0QxcnrOH9OnYcujU0v4KXkCIGO8YwuPclsJFxuLM4mY89o1byEqHbkpHgfoSRCUY3Jb in signatureCipherthe link itself lies and you need to add the decrypted sig to it, the sign itself ( s ) is also attached. How to decrypt signature in signatureCipher ? Anyone who has done this please let me know, or if you have any ideas, looking forward to your answers, thanks!)

Answer 1

Apparently, this is 3d-secure ... If so, then just grunting will not work - banks use it and for a reason. If it is decoded inside the client, then try to find a function that decrypts it and pull it out, see how it decrypts and where it takes the key from.
https://ru.wikipedia.org/wiki/3-D_Secure