It was pointed out to me by Daniel Schumann that I have made some incorrect statements in the original version of Tosefta 6:18, note 5. I have corrected it and posted the new text of that note below. I would like to thank Daniel for providing me with his references.
Tosefta 6:18, Note 5
5. ברוך אתה ה’ אלוהינו מלך העולם אשר קדשנו במצותיו וצונו למול את הגרים ולהטיף מהן דם ברית שאילמלא דם ברית לא נתקיים שמים וארץ שנאמר אם לא בריתי יומם ולילה חקות שמים וארץ לא שמתי. ברוך אתה ה’ כורת הברית. – Blessed You Hashem, our God, King of the world, Who has sanctified us with His commandments and has commanded us to circumsize converts and to draw from them the blood of the covenant, because if not for the blood of the covenant heave and earth would not exist as it is said “If not for my covenant day and night I would not upkeep the laws of heaven and earth.” Blessed You Hashem, Who establishes the convenant.
The Derasha (exegises) that appears in this Beracha appears in two other places. In Tosefta Nedarim 2:6 and in in some editions and manuscripts of the Mishna Nedarim 3:10, in particular as it is printed in Talmud Bavli and as it appears in the Kaufmann manuscript.
The verse in this Beracha from Yirmiyahu 33:25 is taken out of context. In the original intent of the verse God says that just like he upkeeps the laws of heaven and earth so too he will not forsake the Jewish people. However in this Beracha the verse has been taken out of context and reinterpreted, as the Rabbis do often in many places. It seems to me that the reason that the Beracha specifically mentions the procedure of Hatafat Dam Berit is for two reasons. One is so that it would apply even to converts who are already circumcised and two because this specific circumcision has to be done in front of Bet Din as I already explained above in note 2. Since the main thing that the Bet Din have to witness is the drawing of the blood and not the cutting of the foreskin itself the Rabbis specifically emphasized this procedure in the Beracha.
The word אילמלא, which means “if not for” is not really a Hebrew word, but rather it is Aramaic of Babylonian Dialect. See Michael Sokoloff, A Dictionary of Jewish Babybylonian Aramaic, Bar-Ilan University Press, 2002, entry אלמלא. Marcus Jastrow in his Dictionary of the Targumim (entry אלמלא) writes that this word is really a combination of three separate words אילו-מא-לא all of which are Aramaic words. The word אלמלא appears in the Tosefta in a few other places, such as in Sanhedrin 4:5, Nedarim 2:6, and Bava Kama 3:4. It also appears in a few places in the Mishna, (Nedarim 3:10 as printed in the Gemara on Daf 31b and in Kaufmann manuscript 3:16, Taanit 3:8, Kidushin 3:3, Avot 3:2 all in the Muenchen manuscript and Hannoch Albeck Vilna edition) although sometimes it appears in its Palestinian form אילולי which means exactly the same thing but is in Aramaic dialect that was spoken in the Land of Israel. See Michael Sokoloff, A Dictionary of Jewish Palestinian Aramaic, Bar-Ilan University Press, 2002, entry אילולי. That implies that although it was of Babylonian origin it still may have been used in the Land of Israel in the time of the Tannaim or that that Tosefta was edited in Babylon at a later date and that word was inserted into the original text. However in any case it is extremely unlikely that the Tannaim would coin a Beracha with a use of a Babylonian word even if they knew about its existence. Therefore I am inclined to say that although the main text of the Beracha could have been of an earlier origin it was most probably edited later at the time of Talmud Bavli in Babylon and it was put into the text of the Tosefta in the first printed edition based on the text of the Beraita in Talmud Bavli as I mentioned above in note 1.